Coding Requirements

Use the following as guidelines when coding data capture exits:

• We support data capture exits written in COBOL.
• We support a maximum of nine exit routines for any one DBD segment, with no limit on the total number of data capture exits defined for all segments in a DBD.
• One IMS application region supports a maximum of 256 active exit routines. This means that you can define any number of exits in the DBDs referenced by PSBs; however, updates to segments cannot cause more than 256 exits to be called. An exit becomes active as its corresponding database segment is updated and calls the exit.
• We support all fields in the XPCB and XSDB parameter blocks, with appropriate actions for all XPCB return codes.
• Databases that use logical relationships are supported. In these, segment deletes can cascade across a maximum of 32 nested hierarchical relationships and up to a maximum of 99 segment levels.
• Data capture exit programs can make DL/I calls to any PCB defined in the currently active PSB.
• Data capture exits support the following operands:

  EXIT

  • Supported for both DBD and SEGM statements
  • The following options are supported:
    • KEY
    • DATA
    • PATH
    • CASCADE, including the following sub-options:
      • KEY
      • DATA
      Note: We do not support the CASCADE PATH sub-option.
  • The LOG option is not supported, meaning that we do not write data capture log records to disk and therefore are not available for asynchronous processing

  VERSION

  Supported for the DBD statement. The XPCB parameter block points to the value of the VERSION operand. The maximum length of the VERSION value is 128 bytes (after any substitution). If no VERSION operand is specified, a default 13-byte date-time stamp is generated. The &SYSDATE and &SYSTIME substitutable variables are also supported.