A system definition specification that indicates
how a subsystem intends to use a database. During system definition,
a user declares one of four levels of access intent for the subsystem. See also exclusive access, update access, read access, read-only access.
The facility that is used to define, alter, delete,
print, and reproduce VSAM key-sequenced data sets.The internal resource lock manager (IRLM) that supports
the active IMS in
an XRF complex. See also alternate IRLM. In a Remote Site Recovery (RSR) environment, the
data-processing center that contains active IMSs.A range of virtual storage pages that is identified
by a number (ASID) and a collection of segment and page tables that
map the virtual pages to real pages of the computer's memory.A part of IMS TM,
using the common programming interface, which allows IMS application
programs to communicate with other programs by using LU 6.2.AFTER triggerA trigger that is specified to be activated after
a defined trigger event (an insert, update, or delete operation on
the table that is specified in a trigger definition). Contrast with BEFORE trigger and INSTEAD OF trigger.A mapping that an application program uses to interpret
the application interface block (AIB).An
alternative name that can be used in SQL statements to refer to a
table or view in the same or a remote DB2 subsystem.
An alias can be qualified with a schema qualifier and can thereby
be referenced by other users. Contrast with synonym.An area of storage that is external to DB2 and
that is connected to DB2.
An allied address space can request DB2 services. See also address space.A cursor that is defined for a stored procedure result
set by using the SQL ALLOCATE CURSOR statement. In an Extended Recovery Facility (XRF) environment,
the IMS that
monitors the active IMS and
takes over production work when the active IMS fails. Contrast with active IMS.The internal resource lock manager (IRLM) that supports
the alternate IMS in
an Extended Recovery Facility (XRF) complex. See also active IRLM.A user-defined telecommunication-program program
communication block (TP PCB), defined by the user, that can be used
to describe output message destinations other than the terminal that
originated the input message. Where the keyword SAMETRM=YES is not
implicitly or explicitly specified in a PSB, the destination of an
alternate PCB can be either a logical terminal or an input transaction
queue. See also modifiable alternate PCB, express alternate PCB, and alternate response PCB.A program communication block (PCB) that defines
a logical terminal and can be used instead of the I/O PCB when required
to direct a response to a terminal in response mode, conversational
mode, or exclusive mode.A control block that is created from the output of
DBD and PSB generation and placed in the ACB library for use during
online and database batch (DBB) region type execution of IMS.application group name (AGN) securityA commit point that occurs when an application program
issues a checkpoint call. IMS releases
the segments that it has enqueued for the program since the last commit
point; makes permanent the program's changes to the database; and,
if the program processes messages, sends output messages to their
destinations.A system definition option (SEGNO and SEGSIZE keywords)
that enables users to limit the size and number of output segments
that are produced by an application program. This option protects
available message queue space from being depleted by a program output
loop.The name by which VTAM identifies an IMS system
for establishing sessions. The name is specified in a VTAM APPL definition
statement and in the APPLID keyword of the COMM system definition
macro. A subset of a data entry database (DEDB) that is
defined as a VSAM entry-sequenced data set (ESDS). Each area in a
DEDB consists of a root-addressable part, an independent-overflow
part, and a sequential-dependent part. Areas contain the entire logical
structure for a set of root segments and their dependent segments.A data set that contains a data entry database (DEDB)
area. IMS can
maintain up to seven copies of this data set. See also multiple area data set.See level one data sharing.A technique for directing application program printout
output to a specific printer node name. The destination print queue
is specified at logon or signon time, and is created during signon
of the user who created the input transaction.A string that can be verified for connection to DB2 and
to which a set of privileges is allowed. An authorization ID can represent
an individual or an organizational group.A facility that allows an installation to identify
system or user programs that can use sensitive system functions. The option of IMS to
automatically create a VTAM session for a non-signed-on user to whom
output has been made available.Automated Operator (AO)An IMS interface
that allows installations to monitor and control IMS activities.
The interface enables an application program, by using DL/I calls,
to issue a subset of IMS operator
commands and receive command responses; a user exit routine to monitor
activities and take appropriate action; and operator commands, responses,
and asynchronous output that is destined for the IMS master
terminal to be logged to the secondary master terminal.(More correctly automatic rebind.) A
process by which SQL statements are bound automatically (without a
user issuing a BIND command) when an application process begins execution
and the bound application plan or package it requires is not valid. An index on an auxiliary table in which each index
entry refers to a LOB or XML document.A table that contains columns outside the actual
table in which they are defined. Auxiliary tables can contain either
LOB or XML data. availability manager (AVM)The component of z/OS that
performs XRF processing. Specifically, the availability manager performs
I/O prevention during takeover. AVMSee availability manager.An IMS in
a multisystem environment that accepts transactions from the front-end
system, calls application programs for transaction processing, and
routes replies back to the front-end system for response to the terminal.
A back-end system can also perform front-end processing. A back-end
system can be another IMS that
is connected by an MSC link or can be part of the same IMSplex as
the front-end system. See also front-end system.
The
process of undoing uncommitted changes that an application process
made. A backout is often performed in the event of a failure on the
part of an application process, or as a result of a deadlock situation.
The
process of removing all database updates that were made by an application
program that terminated abnormally. See also dynamic backout.The final phase of restart processing during which DB2 scans
the log in a backward direction to apply UNDO log records for all
aborted changes. A common system service base on which many other IMS components
are built. BPE provides a common set of system services such as storage
management, tracing, and dispatching to various components such as
the IMS Common
Queue Server (CQS), IMS Connect,
Operations Manager (OM), Resource Manager (RM), and Structured Call
Interface (SCI).A table that is created by the SQL CREATE TABLE statement
and that holds persistent data. Contrast with clone table, materialized query table, result table, temporary table, and transition table.An IMS function
that performs general message editing for terminal input and output
messages.basic row formatA row format in which values for columns are stored
in the row in the order in which the columns are defined by the CREATE
TABLE statement. Contrast with reordered row format. A copy of a database or area that reflects the state
of the data at a point when no updates were being made. The Database
Image Copy utility (DFSUDMP0) creates batch image copies, which IMS utilities
can use to recover from failures.A BMP program that has access to online databases
and message queues while performing batch processing. A batch-oriented
BMP does not access the IMS message
queues for input or output. It can access online databases, GSAM databases,
and z/OS for
both input and output. See also transaction-oriented BMP.An application program that has access to databases
and z/OS data
management facilities but does not have access to the IMS control
region or its message queues. See also batch message processing program and message processing program.BEFORE triggerA trigger that is specified to be activated before
a defined trigger event (an insert, an update, or a delete operation
on the table that is specified in a trigger definition). Contrast with AFTER trigger and INSTEAD OF trigger.A binary string data type that contains a sequence
of bytes that can range in size from 0 bytes to 2 GB, less 1 byte.
This string does not have an associated code page and character set.
BLOBs can contain, for example, image, audio, or video data. In general,
BLOB values are used whenever a binary string might exceed the limits
of the VARBINARY type.A sequence of bytes that is not associated with a
CCSID. Binary string data type can be further classified as BINARY,
VARBINARY, or BLOB.A
process by which a usable control structure with SQL statements is
generated; the structure is often called an access plan, an application
plan, or a package. During this bind process, access paths to the
data are selected, and some authorization checking is performed. See also automatic bind.A capability in which DB2 can
retrieve, or fetch, a large set of rows together. Using block fetch
can significantly reduce the number of messages that are being sent
across the network. Block fetch applies only to non-rowset cursors
that do not update data.block-level data sharingAn internal component of IMS that
manages buffers. The buffer handler maintains pools of buffers. When
a buffer is needed, the buffer handler selects the buffer at the bottom
of the use chain.To prevent application programs from using invalid
data in a sysplex data-sharing environment, IMS marks
all copies of data in IMS buffers
as invalid after a sharing IMS updates
that data. An
area of memory into which data pages are read, modified, and held
during processing. A
set of buffers that contains buffers of the same length.A data type that IBM supplies.
Among the built-in data types for DB2 for z/OS are
string, numeric, XML, ROWID, and datetime. Contrast with distinct type.A
function that is generated by DB2 and
that is in the SYSIBM schema. Contrast with user-defined function. See also function, cast function, external function, sourced function, and SQL function. A
coupling facility structure that stores data that can be available
to all members of a Sysplex. A DB2 data
sharing group uses cache structures as group buffer pools. One
of the separate sections of the coupling facility storage. The coupling
facility storage is divided, under installation control, into distinct
sections called structures. Services that are provided by IMS for
use by IMS exit
routines. These services provide clearly defined interfaces that allow
exit routines to request various functions, such as acquiring storage
or finding an IMS control
block.A DB2 attachment
facility for application programs that run in TSO or z/OS batch.
The CAF is an alternative to the DSN command processor and provides
greater control over the execution environment. Contrast with Recoverable Resource Manager Services
attachment facility.In an RSR environment, the process by which tracked
log data is used to make all recoverable resources (for example, shadow
databases) current with those resources on the active IMS.The process of creating a compacted version of one
or more IMS log
data sets by eliminating records not related to recovery, and by merging
multiple changes to a single segment into a single change.A character string data type that contains a sequence
of bytes that represent characters (single-byte, multibyte, or both)
that can range in size from 0 bytes to 2 GB, less 1 byte. In general,
CLOB values are used whenever a character string might exceed the
limits of the VARCHAR type.A sequence of bytes that represent bit data, single-byte
characters, or a mixture of single-byte and multibyte characters.
Character data can be further classified as CHARACTER, VARCHAR, or
CLOB.A point at which DB2 records
status information on the DB2 log;
the recovery process uses this information if DB2 abnormally
terminates.Represents
(in this information): CICS Transaction
Server for z/OS:
Customer Information Control System Transaction Server for z/OS.A facility that provides a multithread connection
to DB2 to
allow applications that run in the CICS environment
to execute DB2 statements.The VTAM/NCP communication ID. This value is given
to IMS and
is used by VTAM and IMS to
identify a session between IMS and
a VTAM logical unit.An attribute that is related to a transaction code
and a message region that is used to determine scheduling. See also message class and region class.A terminal that communicates with XRF IMS but
whose sessions are not automatically reestablished at takeover. A terminal for which the alternate IMS pre-opens
backup sessions for the primary sessions that the active IMS opens;
VTAM/NCP switches sessions from primary to backup at takeover.A terminal for which IMS in
the alternate reestablishes service at takeover.clone objectAn object that is associated with a clone table,
including the clone table itself and check constraints, indexes, and
BEFORE triggers on the clone table. clone tableA table that is structurally identical to a base
table. The base and clone table each have separate underlying VSAM
data sets, which are identified by their data set instance numbers. Contrast with base table.An index that determines how rows are physically
ordered (clustered) in a table space. If a clustering
index on a partitioned table is not a partitioning index, the rows
are ordered in cluster sequence within each data partition instead
of spanning partitions. See compatibility mode.See compatibility mode*.The fundamental binary width in a computer architecture
that is used for representing character data, such as 7 bits, 8 bits,
16 bits, or 32 bits. Depending on the character encoding form that
is used, each code point in a coded character set can be represented
by one or more code units. A
process by which DB2 restarts
without processing any log records. Contrast with warm start. The
process of starting IMS when
it is initialized for the first time or when an error condition prevents
a warm start or an emergency restart. See also emergency restart and normal restart.A component of the Control Center for IMS that is
used to issue IMSplex commands from both a workstation or multiple IMS systems.In an IMSplex, the IMS that
an OM designates to process a command when a command is issued through
the OM API. Commands are routed to all IMS systems
that are registered for the command and, if the command requires only
one IMS to
process it, the command master processes the command.A 1- to 8-character command identifier. The command
prefix distinguishes the command as belonging to an application or
subsystem rather than to z/OS.command processing clientcommand significant status The
operation that ends a unit of work by releasing locks so that the
database changes that are made by that unit of work can be perceived
by other processes. Contrast with rollback. To
make changes permanent for a resource in order to establish a new
consistent state. A
point in time when data is considered consistent. The
point at which an application program commits that a section of work
is done and that the data it has modified or created is consistent
and complete. The application program's output, which has been held
until that time, is sent to its destinations, its input is removed
from the message queues, and its database updates are confirmed and
made available to other applications. A commit point occurs when a
program terminates normally or when it issues a checkpoint call or
command. If a program processes messages, a commit point might also
occur when it retrieves a new message.The address space that manages the shared queues
(data objects that are stored in a coupling facility list structure)
for its clients (IMS).In z/OS,
a part of the common area that contains data areas that are addressable
by all address spaces. Most DB2 use
is in the extended CSA, which is above the 16-MB line. A collection of IMS manager
address spaces that provide the infrastructure that is needed for
systems management tasks. The CSL address spaces include RM, OM, and
SCI. The CSL is built on the Base Primitive Environment (BPE) layer.Common Service Layer (CSL) client An IMS control
block that represents a VTAM node or a BTAM line. Each VTAM node or
BTAM line has a single CLB. For VTAM, the block is one of several
blocks that are part of the VTCB control block. The CLB represents
the TM task in the IMS system
for the node or line, and also contains many other fields that pertain
to the node or line.compatibility mode* (CM*)A stage of the version-to-version migration process
that applies to a DB2 subsystem
or data sharing group that was in enabling-new-function mode (ENFM),
enabling-new-function mode* (ENFM*), or new-function mode (NFM) at
one time. Fallback to a prior version is not supported. When in compatibility
mode*, a DB2 data
sharing group cannot coexist with members that are still at the prior
version level. Contrast with compatibility mode, enabling-new-function mode, enabling-new-function mode*,
and new-function mode.
compatibility mode (CM)The first stage of the version-to-version migration
process. In a DB2 data
sharing group, members in compatibility mode can coexist with members
that are still at the prior version level. Fallback to the prior version
is also supported. When in compatibility mode, the DB2 subsystem
cannot use any new functions of the new version. Contrast with compatibility mode*, enabling-new-function mode, enabling-new-function mode*,
and new-function mode.
An ordered set of key columns or expressions of the
same table. The key that is constructed to access a particular
segment. A concatenated key consists of the key fields, including
that of the root segment and successive children, down to the accessed
segment.concurrent image copy (CIC)A batch utility program that enables you to make
a copy of OSAM data sets and VSAM entry-sequenced DBDSs, whether or
not IMS is
running and the database is online.An application's logical connection to the data source
and associated DB2 ODBC
connection information that allows the application to direct its operations
to a data source. A DB2 ODBC
context represents a DB2 thread. A process that occurs when the length of a converted
string is smaller than that of the source string. For example, this
process occurs when an EBCDIC mixed-data string that contains DBCS
characters is converted to ASCII mixed data; the converted string
is shorter because the shift codes are removed.Control Center for IMSA single point of control with a graphical interface
that simplifies system management tasks in an IMSplex environment.
Administrators can work with a consolidated system view and manage
all their IMS systems
from a single workstation. A
fixed-length area of direct access storage in which VSAM stores records
and creates distributed free space. Also, in a key-sequenced data
set or file, the set of records that are pointed to by an entry in
the sequence-set index record. The control interval is the unit of
information that VSAM transmits to or from direct access storage.
A control interval always comprises an integral number of physical
records.An indicator that is used in a data-sharing environment
to determine which sharing partner last read a CI. IMS compares
the value of the CUSN for each CI to determine whether a CI should
be updated during area restart or recovery. Communication,
which is based on LU 6.2 or Advanced Program-to-Program Communication
(APPC), between an application and a remote transaction program over
an SNA logical unit-to-logical unit (LU-LU) session that allows communication
while processing a transaction. A
dialog between a terminal and a message processing program using IMS conversational
processing facilities. Also, a dialog between an LU 6.2 program and
an IMS application
program. A conversation between a terminal and a message processing
program is significant status that is kept in the RM, if the RM is
used. Status for a held conversation is not kept in the RM. The IMS conversation
is represented by a CCB. See also conversational processing.An optional facility that allows an application program
to accumulate information acquired through multiple interchanges with
a terminal, even though the program terminates between interchanges.
Conversation information for the active and held conversations is
significant status that can optionally be kept in the RM if a status
recovery mode of GLOBAL is selected.A z/OS subsystem
that consists of the database resource adapter (DRA) and a transaction
management subsystem, such as CICS.
A CCTL provides communications and transaction management services
for a DBCTL environment, which has no transaction management facilities
of its own.See SQL statement coprocessor.A collection of names of storage groups that are
processed collectively for fast replication operations. An
identifier that is specified and used within a single SQL statement
as the exposed name for objects such as a table, view, table function
reference, nested table expression, or result of a data change statement.
Correlation names are useful in an SQL statement to allow two distinct
references to the same base table and to allow an alternative name
to be used to represent an object. A
special PR/SM logical partition (LPAR) that runs the coupling facility
control program and provides high-speed caching, list processing,
and locking functions in a Parallel Sysplex. A
special logical partition that provides high-speed caching, list processing,
and locking functions in a sysplex. IMS saves
global information in the coupling facility, so all the IMSs in
the IMSplex have access to the global information.The process by which CQS starts: either a cold start
or a warm start. During a CQS warm start, the CQS environment is restored
to its state when CQS terminated. During a CQS cold start, the CQS
environment is not restored to its previous state; it is reinitialized.In an IMS database,
the place immediately preceding the segment occurrence that IMS retrieves
if you immediately issue an unqualified retrieval call. A
control structure that an application program uses to point to a single
row or multiple rows within some ordered set of rows of a result table.
A cursor can be used to retrieve, update, or delete rows from a result
table. During
a HALDB online reorganization, a marker in a database partition that
separates the copied database records from the records that have not
been copied. The cursor indicates the progress of the reorganization
through the HALDB partition.For HALDB online reorganization, the status in the
RECON data set that tells DBRC that an online reorganization has started.The internal representation of a cursor. See control interval update sequence number. A set of tables that can be ordered so that each
table is a descendent of the one before it, and the first table is
a descendent of the last table. A self-referencing table is a cycle
with a single member. See also referential cycle. A
collection of tables, or a collection of table spaces and index spaces. A
collection of data that is arranged in a hierarchical (tree) structure.
At each level of the hierarchy, data is related to, and dependent
on, data at the higher level of the hierarchy. Data is stored within
the database only once and is available to any user who is authorized
to use it. Users do not need to have personal copies of the data.A thread that accesses data at the local subsystem
on behalf of a remote subsystem. An environment that allows full-function databases
and DEDBs to be accessed from one or more transaction management subsystems.Database Control (DBCTL) environmentThe IMS DB/DC
environment without the message handling and queue management capabilities.A data set that contains some or all of the database
records that are stored in a full-function database. Other types of
data sets that are used in IMS databases
include Fast Path area data sets, HALDB indirect list data sets, and
HALDB primary index data sets.The protection of data items in a database while
they are available to any application program. This protection includes
the isolation of effects of concurrent updates to a database by two
or more application programs.database-level data sharingdatabase-level trackingThe PCB that describes an application program's interface
to a database. One DB PCB is required for each database view that
is used by the application program. In a database, a collection of segments that contains
one occurrence of the root segment type and all of its dependents
arranged in a hierarchic sequence. A database record can be a physical
database record or a logical database record. See also physical database record and logical database record.The process of restoring a physically or logically
damaged DBDS by merging an image copy and logs or change accumulation
data sets.A feature of the IMS Database
Manager that facilitates easier recovery of IMS databases.
DBRC maintains information that is required for database recoveries,
generates recovery control statements, verifies recovery input, maintains
a separate change log for database data sets, and supports sharing
of IMS databases
and areas by multiple IMS subsystems.An interface to IMS DB
full-function databases and DEDBs. The DRA can be used by a coordinator
controller (CCTL) or by a z/OS application
program that uses the ODBA interface. Obsolete term. See telecommunication program PCB.Part of a coupling facility list structure list entry
that is used to hold user-specified data.A direct-access database that consists of one or
more areas, with each area containing both root segments and dependent
segments. DEDBs use a data structure that allows them to be used for
both hierarchic processing and journaling. The database is accessed
by using the VSAM Media Manager. The IMS data
manipulation language, which is a common high-level interface between
a user application and IMS.
DL/I calls are invoked from application programs that are written
in languages such as Java, PL/I, COBOL, VS Pascal, C, and Ada. DL/I
can also be invoked from assembler language application programs by
subroutine calls. IMS lets
the user define data structures, relate structures to the application,
load structures, and reorganize structures.An IMS control
block in main storage that describes and controls a physical database.
A DMB is constructed from information that is obtained from the ACB
library or the DBD library.A piece of client data that is placed on the coupling
facility by CQS as a result of a CQSPUT request or a CQSUPD request.
From an IMS shared
queues point of view, a data object contains one part or all of an IMS message
or an entire EMH message. From an IMS Resource
Manager point of view, a data object contains information about an IMS resource
such as a transaction or a user.An operating system data set that contains a subset
of a database with one or more unique segment types. A database always
consists of at least one data set group. See also primary data set group and secondary data set group.data set instance numberA number that indicates the data set that contains
the data for an object.data set sequence number (DSSN) A
function of DB2 for z/OS that
enables applications on different DB2 subsystems
to read from and write to the same data concurrently. The
concurrent access of databases by two or more IMSs.
The IMSs can
be in one operating system image or in separate operating system images.
The IMSs can share data at two levels: the database level and the
block level. See block-level sharing and database-level sharing.data-sharing group A
collection of one or more DB2 subsystems
that directly access and change the same data while maintaining data
integrity. The
components that are involved in sysplex data sharing. Among the components
are the sharing IMSs,
the IRLMs they use, the lock, OSAM, and VSAM structures in the coupling
facility, and a single set of DBRC RECON data sets.An attribute of an input message that causes ISC
edit to route the message to its destination without examination or
modification.An attribute of columns, constants, variables, parameters,
special registers, and the results of functions and expressions. See database access thread. One of two batch regions (the other being a DL/I
batch region). DBB is an execution parameter. DBB batch jobs contain
JCL DD statements for the ACB library.A field that contains both DBCS and EBCDIC data.
The DBCS portions should always be enclosed with SO/SI control characters
in both inbound and outbound data. In the case of inbound data, the
control characters are automatically created by the terminal. Database/data communication.DBRC groupIn IMS Version
10, one or more DBRC instances that share a single RECON data set
in an IMSplex environment. Each DBRC group has a group identifier
(GROUP ID), which is unique for that group. DBRC groups are used by
DBRC, whether or not parallel RECON access is enabled.DBRC requestAn action (command process, query, and update) that is asked of
DBRC by IMS,
DBRC application programs, and jobs.The database manager structure that describes an
application's connection, traces its progress, processes resource
functions, and delimits its accessibility to the database manager
resources and services. Most DB2 for z/OS functions
execute under a thread structure.DC PCBObsolete term. See telecommunication program PCB.DCTSee device characteristics table.In MFS, part of the device output format (DOF) that
causes specific terminal functions to be performed if the destination
terminal has the required features. See also system control area.A predetermined value, attribute, or option that
is assumed when no other value is specified. A default value can be
defined for column data in DB2 tables
by specifying the DEFAULT keyword in an SQL statement that changes
data (such as INSERT, UPDATE, and MERGE).A trigger that is defined with the triggering delete
SQL operation.A sequence of characters that are enclosed within
escape characters.In a database, a segment that relies on a higher-level
segment for its full hierarchic meaning. A child is a dependent segment
of its parent. Contrast with root segment.An element of the active IMS system
that has a counterpart in the alternate IMS system,
but cannot trigger a takeover on its own. z/OS,
VTAM, IRLM, and the CPC are DSEs. A DSE depends on IMS to
recognize a failure in its processing and request that the alternate
take over its operation.In IMS TM,
an application program, a logical terminal, or an operator command
that is associated with the control region.In a database, the physical or logical parent that
is reached by the logical child path.A user-defined function whose result is dependent
on the values of the input arguments. That is, successive invocations
with the same input values produce the same answer. Sometimes referred
to as a not-variant function. Contrast with nondeterministic function (sometimes
called a variant function).device characteristics table (DCT)An MFS table that is generated for IBM 3270
or SLU type 2 devices with symbolic names. An entry is generated for
each symbolic name and its associated screen size and physical terminal
features. Different combinations of features for the same symbolic
name cause separate entries in the table to be created.In MFS, the smallest area in a device input format
(DIF) or device output format (DOF) whose content and structure are
defined by the user.The MFS control block that describes the format of
the data that is entered on the device and presented to MFS.The MFS control block that describes the format of
the output data that is presented to the device. In a DEDB, a segment that is chained from a root
segment. A direct dependent segment is stored in either the root addressable
portion or the overflow portion of a DEDB area.A user-defined data type that is represented as an
existing type (its source type), but is considered to be a separate
and incompatible type for semantic purposes.An address space that is used by the online IMS control
program to contain most of the DL/I code and control blocks. This
option can be selected for the online IMS environment
to provide an alternative virtual storage configuration.DOCIDSee document ID.document IDA value that uniquely identifies a row that contains
an XML column. This value is stored with the row and never changes. A graphic string data type in which a sequence of
bytes represent double-byte characters that range in size from 0 bytes
to 2 GB, less 1 byte. In general, DBCLOB values are used whenever
a double-byte character string might exceed the limits of the VARGRAPHIC
type.See dynamic resource definition. dynamic resource definition (DRD)An IMS function
that enables users to create, update, query, and delete the following IMS resources
and their descriptors dynamically, without using the batch system
definition or online change processes: application programs; databases;
Fast Path routing codes; transactions.SQL statements that are prepared and executed at
run time. In dynamic SQL, the SQL statement is contained as a character
string in a host variable or as a constant, and it is not precompiled. enabling-new-function mode* (ENFM*)A transitional stage of the version-to-version migration
process that applies to a DB2 subsystem
or data sharing group that was in new-function mode (NFM) at one time.
When in enabling-new-function mode*, a DB2 subsystem
or data sharing group is preparing to use the new functions of the
new version but cannot yet use them. A data sharing group that is
in enabling-new-function mode* cannot coexist with members that are
still at the prior version level. Fallback to a prior version is not
supported. Contrast with compatibility mode, compatibility mode*, enabling-new-function mode,
and new-function mode.enabling-new-function mode (ENFM)A transitional stage of the version-to-version migration
process during which the DB2 subsystem
or data sharing group is preparing to use the new functions of the
new version. When in enabling-new-function mode, a DB2 data
sharing group cannot coexist with members that are still at the prior
version level. Fallback to a prior version is not supported, and new
functions of the new version are not available for use in enabling-new-function
mode. Contrast with compatibility mode, compatibility mode*, enabling-new-function mode*,
and new-function mode. In Language Environment, an independent collection
of routines, one of which is designated as the main routine. An enclave
is similar to a program or run unit. See also WLM enclave. A type of significant status that relates to the
work associated with a resource. IMS defines
conversations, set-and-test-sequence numbers terminals, and Fast Path
as end-user significant status for nodes and users.See enabling-new-function mode.See enabling-new-function mode*.A person, object, or concept about which information
is stored. In a relational database, entities are represented as tables.
A database includes information about the entities in an organization
or business, and their relationships to each other. A handle that identifies the global context for database
access. All data that is pertinent to all objects in the environment
is associated with this handle. A piece of data that is maintained for a Fast Path
area data set block that cannot be accessed. Each data set can have
up to ten damaged blocks (control intervals).An SQL operation that involves the EXCEPT set operator,
which combines two result tables. The result of an exception operation
consists of all of the rows that are in only one of the result tables.A privilege that has a name and is held as the result
of an SQL GRANT statement and revoked as the result of an SQL REVOKE
statement. For example, the SELECT privilege. A
facility that minimizes the effect of failures in z/OS,
VTAM, the host processor, or high-availability applications during
sessions between high-availability applications and designated terminals.
This facility provides an alternative subsystem to take over sessions
from the failing subsystem. A
function of IMS that
minimizes the impact of IMS failures
by having an alternate IMS monitor
an active IMS and
take over production if the active IMS fails. A feature of IMS Transaction Manager that enables
users to add or delete ACF/VTAM terminals or message queues (LTERMs)
dynamically.A function that has its functional logic implemented
in a programming language application that resides outside the database,
in the file system of the database server. The association of the
function with the external code application is specified by the EXTERNAL
clause in the CREATE FUNCTION statement. External functions can be
classified as external scalar functions and external table functions. Contrast with sourced function, built-in function, and SQL function.A procedure that has its procedural logic implemented
in an external programming language application. The association of
the procedure with the external application is specified by a CREATE
PROCEDURE statement with a LANGUAGE clause that has a value other
than SQL and an EXTERNAL clause that implicitly or explicitly specifies
the name of the external application. Contrast with external SQL procedure and native SQL procedure.external SQL procedureAn SQL procedure that is processed using a generated
C program that is a representation of the procedure. When an external
SQL procedure is called, the C program representation of the procedure
is executed in a stored procedures address space. Contrast with external procedure and native SQL procedure. The process of returning to a previous release of DB2 after
attempting or completing migration to a current release. Fallback
is supported only from a subsystem that is in compatibility mode. A direct physical access path to data, which is provided
by an index, hash, or link; a fan set is the means by which DB2 supports
the ordering of data. fast replication image copyA type of image copy that is taken by the Database Image Copy
2 utility by using the DFSMS fast replication option and either the
FlashCopy function of the Enterprise Storage Server (ESS) hardware
or the SnapShot copy function of the RAMAC Virtual Array (RVA).The specification of the desired placement of the
cursor as part of a FETCH statement. The specification can be before
or after the rows of the result table (with BEFORE or AFTER). The
specification can also have either a single-row fetch orientation
(for example, NEXT, LAST, or ABSOLUTE n)
or a rowset fetch orientation (for example, NEXT ROWSET, LAST ROWSET,
or ROWSET STARTING AT ABSOLUTE n).file reference variableA host variable that is declared with one of the
derived data types (BLOB_FILE, CLOB_FILE, DBCLOB_FILE); file reference
variables direct the reading of a LOB from a file or the writing of
a LOB into a file.A character, graphic, or binary string whose length
is specified and cannot be changed. Contrast with varying-length string.A function on the IBM Enterprise
Storage Server that can, in conjunction with the BACKUP SYSTEM utility,
create a point-in-time copy of data while an application is running. In a hierarchical direct database, the first four
bytes of a CI or block. The first 2-byte field contains the offset,
in bytes, to the first FSE in the CI or block. The second 2-byte field
identifies whether this block or CI contains a bit map.fullselectA subselect, a fullselect in parentheses, or a number
of both that are combined by set operators. Fullselect specifies a
result table. If a set operator is not used, the result of the fullselect
is the result of the specified subselect or fullselect.Functions can be user-defined, built-in, or generated by DB2. (See also built-in function, cast function, external function, sourced function, SQL function, and user-defined function.)
geographic featureAn object on the surface of the Earth (such as a city or river),
a space (such as a safety zone around a hazardous site), or an event
that occurs at a location (such as an auto accident that occurred
at a particular intersection).geographic information systemA complex of objects, data, and applications that is used to create
and analyze spatial information about geographic features. A
lock that provides concurrency control within and among DB2 subsystems.
The scope of the lock is across all DB2 subsystems
of a data sharing group. An
IRLM lock that interests two IRLMs; both must coordinate to grant
it.A sequence of DBCS characters. Graphic data can be
further classified as GRAPHIC, VARGRAPHIC, or DBCLOB.GRECPSee group buffer pool recovery pending.group buffer pool recovery pending
(GRECP)The state that exists after the buffer pool for a
data sharing group is lost. When a page set is in this state, changes
that are recorded in the log must be applied to the affected page
set before the page set can be used.See generalized trace facility. histogram statisticsA way of summarizing data distribution. This technique
divides up the range of possible values in a data set into intervals,
such that each interval contains approximately the same percentage
of the values. A set of statistics are collected for each interval.In an application program written in a host language,
an application variable that is referenced by embedded SQL statements. A specialized processor that can be used for some DB2 functions.A column that provides a way for DB2 to
automatically generate a numeric value for each row. Identity columns
are defined with the AS IDENTITY clause. Uniqueness of values can
be ensured by defining a unique index that contains only the identity
column. A table can have no more than one identity column. An
exact reproduction of all or part of a table space. DB2 provides
utility programs to make full image copies (to copy the entire table
space) or incremental image copies (to copy only those pages that
have been modified since the last image copy). The
process of creating a backup of a DBDS. The backup data set created
by the image copy process. See also fuzzy image copy.IMS control programIMS Database Manager (IMS DB)The IMS Database
Manager licensed program, which processes concurrent database calls
and offers high performance for a variety of applications.IMS JDBC driverA driver that provides a connection to the IMS database,
which enables users to access and change the database by using SQL
queries.IMS Transaction Manager (IMS TM)The IMS Transaction
Manager licensed program, a data communication system that provides
high-volume, high-performance, high-capacity, low-cost transaction
processing for both IMS Database
Manager (IMS DB) and DB2 databases. A status of a unit of recovery. If DB2 fails
after it has finished its phase 1 commit processing and before it
has started phase 2, only the commit coordinator knows if an individual
unit of recovery is to be committed or rolled back. At restart, if DB2 lacks
the information it needs to make this decision, the status of the
unit of recovery is indoubt until DB2 obtains
this information from the coordinator. More than one unit of recovery
can be indoubt at restart. A
status of a unit of recovery. If DB2 fails
before its unit of recovery completes phase 1 of the commit process,
it merely backs out the updates of its unit of recovery at restart.
These units of recovery are termed inflight. The
state of a resource or unit of recovery that has not yet completed
the prepare phase of the commit process.input output area input (IOAI)An I/O area that is used by the Fast Path DL/I calls that return
structural information about DEDBs.A trigger that is defined with the triggering SQL
operation, an insert.installation verification program (IVP)A procedure that is integral to the IMS installation
process, and that tests the newly-installed IMS system
to verify that the basic facilities of IMS are
functioning properly. The jobs and tasks of the IVP also build a sample IMS system
and provide several sample applications that are used to verify specific
components of IMS.INSTEAD OF triggerA trigger that is associated with a single view and
is activated by an insert, update, or delete operation on the view
and that can define how to propagate the insert, update, or delete
operation on the view to the underlying tables of the view. Contrast with BEFORE trigger and AFTER trigger. A z/OS subsystem
that DB2 uses
to control communication and database locking. A
subsystem in a z/OS environment
that provides lock management, and is used by IMSs to
share data.intersectionAn SQL operation that involves the INTERSECT set
operator, which combines two result tables. The result of an intersection
operation consists of all of the rows that are in both result tables.An extension of IMS Multiple
Systems Coupling (MSC) that permits the connection of IMS to
another IMS subsystem,
to CICS on z/OS,
or to a user-written subsystem, as long as both subsystems use ISC.
Also known as LU 6.1.IOAISee input/output program communication
block.A value that uniquely identifies a TCP/IP host. isolated log sender (ILS)Java class libraries for IMSA Java library that allows JDBC access to IMS databases
from JMP or JBP applications, WebSphere Application Server for z/OS Enterprise
JavaBeans (EJBs), CICS JCICS
applications, and DB2 for z/OS stored
procedures. A column, an ordered collection of columns, or an
expression that is identified in the description of a table, index,
or referential constraint. The same column or expression can be part
of more than one key.See key-sequenced data set. A DB2 mechanism
for controlling concurrent events or the use of system resources. A
programming device that provides short-term serialization for IMS tasks
that are running in the online IMS system.
Similar in function to a z/OS lock.An index page that contains pairs of keys and RIDs
and that points to actual data. Contrast with nonleaf page. Anchors the list to a coupling facility list structure
and contains control information associated with the list. A
coupling facility structure that lets data be shared and manipulated
as elements of a queue. A
coupling facility structure that enables multisystem applications
in a sysplex to share information organized as a set of lists or queues.
A list structure consists of a set of lists and an optional lock table,
which can be used for serializing resources in the list structure.
Each list consists of a queue of list entries.load balancingAn optional Fast Path facility that enables an application
program to be scheduled into more than one message or batch message
region at the same time. See also transaction load balancing.load balancing groupA grouping of Fast Path input messages that are ready
for balanced processing by one or more copies of a Fast Path program.
There is one load balancing group for each unique Fast Path message-driven
application program.A table space that contains all the data for a particular
LOB column in the related base table. A
lock that provides intra-DB2 concurrency
control, but not inter-DB2 concurrency
control; that is, its scope is a single DB2. An
IRLM lock that interests the IRLM that grants it only.local logical unit (local LU)Any logical unit (LU), other than the defined base LU, that is
used for outbound processing. See also logical unit.The process by which the integrity of data is ensured.
Locking prevents concurrent users from accessing inconsistent data. See also claim, drain, and latch. An
access point through which an application program accesses the SNA
network in order to communicate with another application program. See also LU name. An
addressable resource such as an application program, a terminal, or
a subsystem. A logical unit can also be a component of general-purpose
terminal systems, such as operator terminals, printers, and auxiliary
control units. For IMS,
an LU is usually a terminal that logs on to IMS to
do work. The
processing that a program performs between synchronization points. The
processing a program performs from one sync point to the next.A prefix, in every log record, that contains control
information.A token that identifies a particular log record in
the z/OS log
stream that is used to locate that log record.An LU 6.2 application program that is defined by
an LU (logical unit) name, plus a transaction program name. See logical unit of work identifier. See multiple area data set.A table that is used to contain information that
is derived and can be summarized from one or more source tables. Contrast with base table.See multibyte character set. message flood conditionWhen the number of incoming messages that are waiting to be processed
by OTMA threatens IMS performance
or rises above acceptable limits. A message flood condition occurs
when too many transactions are waiting to be processed by OTMA, and
can deplete all available local system queue area (LSQA) storage and
result in a z/OS abend.A technique that is used by the online IMS control
program, when operating under z/OS,
to manage message format control blocks that are stored in extended
private storage.MSC directed routingA character set that represents single characters
with more than a single byte. UTF-8 is an example of an MBCS. Characters
in UTF-8 can range from 1 to 4 bytes in DB2. Contrast with single-byte character set and double-byte character set. See also Unicode. multiple area data set (MADS)A 1-byte number from 1 to 255 that the client specifies
as the first byte of the resource ID. The name type guarantees uniqueness
of names for all resources of that name type. This uniqueness prevents
clients from putting more than one resource with the same name and
name type out on the resource structure. The resources within the
name type can have different data resource types.native SQL procedureAn SQL procedure that is processed by converting
the procedural statements to a native representation that is stored
in the database directory, as is done with other SQL statements. When
a native SQL procedure is called, the native representation is loaded
from the directory, and DB2 executes
the procedure. Contrast with external procedure and external SQL procedure. new-function mode (NFM)The normal mode of operation that exists after successful
completion of a version-to-version migration. At this stage, all new
functions of the new version are available for use. A DB2 data
sharing group cannot coexist with members that are still at the prior
version level, and fallback to a prior version is not supported. Contrast with compatibility mode, compatibility mode*, enabling-new-function mode,
and enabling-new-function mode*.See new-function mode.An IMS resource
that represents a physical VTAM terminal. The node is represented
by a VTAM termincal control block (TCB).node ID indexSee XML node ID index. A user-defined function whose result is not solely
dependent on the values of the input arguments. That is, successive
invocations with the same argument values can produce a different
answer. This type of function is sometimes called a variant function. Contrast with deterministic function (sometimes
called a not-variant function).A page that contains keys and page numbers of other
pages in the index (either leaf or nonleaf pages). Nonleaf pages never
point to actual data. Contrast with leaf page. In C, the value that indicates the end of a string.
For EBCDIC, ASCII, and Unicode UTF-8 strings, the null terminator
is a single-byte value (X'00'). For Unicode UTF-16 or UCS-2
(wide) strings, the null terminator is a double-byte value (X'0000'). OLAPSee online analytical processing.online analytical processing (OLAP)The process of collecting data from one or many sources;
transforming and analyzing the consolidated data quickly and interactively;
and examining the results across different dimensions of the data
by looking for patterns, trends, and exceptions within complex relationships
of that data.In an RSR environment, the process by which a stopped
shadow database or area is brought to currency with the database or
area on the active IMS by
the tracking IMS.The process of creating an image copy while the database
is online. Also, the image copy that is created by the online image
copy process.The name of an object that is used for an application
package or an SQL procedure package. An application package is a bound
version of a database request module (DBRM) that is created by a BIND
PACKAGE or REBIND PACKAGE command. An SQL procedural language package
is created by a CREATE or ALTER PROCEDURE statement for a native SQL
procedure. The name of a package consists of a location name, a collection
ID, a package ID, and a version ID. A unit of storage within a table space (4 KB, 8 KB,
16 KB, or 32 KB) or index space (4 KB, 8 KB, 16 KB, or 32 KB). In
a table space, a page contains one or more rows of a table. In a LOB
or XML table space, a LOB or XML value can span more than one page,
but no more than one LOB or XML value is stored on a page.A question mark (?) that appears in a statement string
of a dynamic SQL statement. The question mark can appear where a variable
could appear if the statement string were a static SQL statement. An SQL identifier that designates a parameter in
a routine that is written by a user. Parameter names are required
for SQL procedures and SQL functions, and they are used in the body
of the routine to refer to the values of the parameters. Parameter
names are optional for external routines. A
portion of a page set. Each partition corresponds to a single, independently
extendable data set. The maximum size of a partition depends on the
number of partitions in the partitioned page set. All partitions of
a given page set have the same maximum size. partition-by-growth table spaceA table space whose size can grow to accommodate
data growth. DB2 for z/OS manages
partition-by-growth table spaces by automatically adding new data
sets when the database needs more space to satisfy an insert operation. Contrast with range-partitioned table space. See also universal table space.A data set in disk storage that is divided into partitions,
which are called members. Each partition can contain a program, part
of a program, or data. A program library is an example of a partitioned
data set. A table space that is based on a single table and
that is subdivided into partitions, each of which can be processed
independently by utilities. Contrast with segmented table space and universal table space. See SQL path. The process of preparing a VSAM linear data set for DB2 use,
by writing specific data patterns. A
VTAM conversation that supports two-phase commit flows. A
communication session that is allocated between two programs processing
a transaction, that uses the sync point option, and that uses the
two-phase commit and resynchronization protocols.The part of a query that is represented by one of
the FROM clauses. Each FROM clause can have multiple query blocks,
depending on DB2 processing
of the query.queuequeue bufferAn IMS queue
manager incore buffer that is used to keep the working copy of an IMS message
segment.The normal OSAM buffering method, which reads only
one block with each I/O operation.range-partitioned table spaceA type of universal table space that is based on
partitioning ranges and that contains a single table. Contrast with partition-by-growth table space. See also universal table space. Rapid Network Reconnect (RNR)RDDSSee resource definition data set.RDOSee resource definition online. For an RSR database-level tracker, the level that
determines whether a shadow database is ready to apply database changes
as they are received from the active IMS. An access intent that establishes the intent of an
application to read the database without being protected from an updater's
incomplete changes. Also called read
without integrity.A unique identifier that DB2 uses
to identify a row of data in a table. Compare with row identifier.An IMS service
element that is backed up and that can initiate a takeover.recovery-level trackingIn an RSR environment, a tracking IMS that
does not track the databases or areas of the active IMSs, but instead
saves all database changes on tracked logs on the tracking IMS until
recovery or remote takeover is performed. See also database-level tracking.referential cycleA set of referential constraints such that each base
table in the set is a descendent of itself. The tables that are involved
in a referential cycle are ordered so that each table is a descendent
of the one before it, and the first table is a descendent of the last
table. relational schemaSee SQL schema. reordered row formatA row format that facilitates improved performance
in retrieval of rows that have varying-length columns. DB2 rearranges
the column order, as defined in the CREATE TABLE statement, so that
the fixed-length columns are stored at the beginning of the row and
the varying-length columns are stored at the end of the row. Contrast with basic row format.A construct of previous versions of the CICS attachment
facility that defines authorization and access attributes for transactions
or transaction groups. Beginning in CICS Transaction
Server Version 1.3, resources are defined by using resource definition
online instead of the resource control table. See also resource definition online.resource definition data set (RDDS)A data set that manages IMS resources. IMS systems
have options to export resources that are defined by the system definition
process and resources that have been created or updated dynamically,
into the RDDS. These resources can then be imported from the RDDS
into an IMS system
during cold start processing or through the use of an IMPORT command.resource definition memberA member in the IMS.PROCLIB data set that defines the resource
definition data set (RDDS) to IMS. See also resource definition data set.The recommended method of defining resources to CICS by
creating resource definitions interactively, or by using a utility,
and then storing them in the CICS definition
data set. In earlier releases of CICS,
resources were defined by using the resource control table (RCT),
which is no longer supported.resource descriptorTemplates in which you define the attributes for a resource. You
can then create a resource by using the resource descriptor to define
the attributes for the resource.The programmable list entry ID that IMS specifies
for a resource to ensure name uniqueness. The first byte is the name
type, and the remaining 11 bytes are the resource name, padded with
blanks.An 11-byte unique name of a client-defined resource.
A transaction is an example of an IMS resource
name.A resource that is defined by CQS. CQS groups list
headers into resource types. The resource types allow CQS and its
clients to physically group resources of a particular type on a coupling
facility list structure.A MODIFY lock that a DB2 subsystem
was holding at the time of a subsystem failure. The lock is retained
in the coupling facility lock structure across a DB2 for z/OS failure.When RM and a resource structure are used, an association
between an IMS and
a user or node with LOCAL status recovery mode. If RM indicates that
the user or node has RM affinity to an IMS,
the user or node cannot log or sign on to another IMS.
This affinity occurs because end-user significant status (conversation,
set-and-test-sequence-numbers terminal, or Fast Path) is being recovered
on an IMS.roleA database entity that groups together one or more
privileges and that can be assigned to a primary authorization ID
or to PUBLIC. The role is available only in a trusted context. A database object that encapsulates procedural logic
and SQL statements, is stored on the database server, and can be invoked
from an SQL statement or by using the CALL statement. The main classes
of routines are procedures and functions. The specification of the desired placement of the
cursor as part of a FETCH statement, with respect to a single row
(for example, NEXT, LAST, or ABSOLUTE n). Contrast with rowset-positioned fetch orientation.The specification of the desired placement of the
cursor as part of a FETCH statement, with respect to a rowset (for
example, NEXT ROWSET, LAST ROWSET, or ROWSET STARTING AT ABSOLUTE n). Contrast with row-positioned fetch orientation.runtime descriptor definitionThe runtime template (in an internal format of control blocks)
that can be used as a model when creating runtime resource definitions. See also runtime resource definition.runtime resource definitionThe resource information such as attributes, status, and relationships
to other resources that IMS maintains
at run time in an internal format called control blocks. The runtime
resource definitions include, but are not limited to, database directories
(DDIRs), program directories (PDIRs), data management blocks (DMBs),
program specification blocks (PSBs), Fast Path routing codes (RCTEs),
and scheduler message blocks (SMBs) or transactions.See single-byte character set. See shared communications area. See system control area.An
SQL operation that produces a single value from another value and
is expressed as a function name, followed by a list of arguments that
are enclosed in parentheses. An application program attribute that is defined
in the PSB, and that specifies how the program should be scheduled
if multiple programs are contending for scheduling. See also exclusive
access, read-only access, read access,
and update access.An index that is used to establish accessibility
to a physical or logical database by a path that is different from
the one provided by the database definition. A secondary index contains
an index pointer segment type that is defined in a secondary index
database.security labelA classification of users' access to objects or data
rows in a multilevel security environment." A
group of pages that holds rows of a single table. See also segmented table space. The
unit of access; for the DB system, the smallest amount of data that
can be transferred by one IMS operation.
For input terminal operations using IMS TM,
a segment is defined by the particular terminal type and is obtained
by an application program with one call. See also segment occurrence and message segment.A table space that is divided into equal-sized groups
of pages called segments. Segments are assigned to tables so that
rows of different tables are never stored in the same segment. Contrast with partitioned table space and universal table space.A unit of work that is scheduled to execute.set operatorThe SQL operators UNION, EXCEPT, and INTERSECT corresponding
to the relational operators union, difference, and intersection. A
set operator derives a result table by combining two other result
tables. A
request that is made on behalf of an individual CICS or IMS application
process by an attachment facility to enable DB2 to
verify that it is authorized to use DB2 resources. The
act a terminal user performs in order to identify a user to IMS.
When the terminal is an ETO terminal, the signon process also creates
a user structure and connects the user structure to the terminal structure.A table space that is neither partitioned nor segmented.
Creation of simple table spaces is not supported in DB2 Version
9.1 for z/OS</