DBCAIRX is used for initiating requests. It is of variable length, is not initialized by DBCHINI, and is allocated by the application.
The DBCAREA Extension Pointer field points to DBCAIRX. DBCAIRX does not exist if there is a zero in the DBCAREA Extension Pointer field.
The prologue for the Assembler, COBOL, C, and PL/I mappings of the DBCAIRX provides language-dependent information in constructing an extension and should be consulted.
The application should set unused fields to binary zeroes. This will allow successful execution of existing applications should these fields ever be used.