ALLOCATE DESCRIPTOR

>>-ALLOCATE DESCRIPTOR--+-'descriptor'---+---------------------->
                        '-descriptor_var-'
 
>--+-------------------------+---------------------------------><
   '-WITH MAX--+-items-----+-'
               '-items_var-'

Element	Description	Restrictions	Syntax
descriptor	Name of an unallocated system-descriptor area	Enclose in single ( ' ) quotes. Must be unique among SDA names	Quoted String.
descriptor_var	Host variable that stores the name of a system-descriptor area	Must contain name of unallocated system-descriptor area	Language specific
items	Number of item descriptors in descriptor. Default value is `100`.	Must be an unsigned INTEGER greater than zero	Literal Number
items_var	Host variable that contains the number of items	Data type must be INTEGER or SMALLINT	Language specific

The ALLOCATE DESCRIPTOR statement creates a system-descriptor area, which is a location in memory that holds information that the DESCRIBE statement can display, or that holds information about the WHERE clause of a query.

A system-descriptor area (SDA) contains one or more fields called item descriptors. Each item descriptor holds a data value that the database server can receive or send. The item descriptors also contain information about the data, such as data type, length, scale, precision, and nullability.

A system-descriptor area holds information that a DESCRIBE...USING SQL DESCRIPTOR statement obtains or that holds information about the WHERE clause of a dynamically executed statement.

If the name that you assign to a system-descriptor area matches the name of an existing system-descriptor area, the database server returns an error. If you free the descriptor with the DEALLOCATE DESCRIPTOR statement, however, you can reuse the same descriptor name.

ALLOCATE DESCRIPTOR

Syntax

Usage