ATC0137 Support ID checking (exit DXCUPIDC) for fixed as well as pool records.

Following is the original requirement statement as expressed by sponsor, and does not reflect priority agreed by user group.

ALCS VERSION NO:

DATE: September 1994

REQUEST SPONSOR: SAA

REQUEST PRIORITY: 2

1. PROBLEM DESCRIPTION:

ID checking should be supported for fixed records and not just pool.

2. STATEMENT OF REQUIREMENT:

Userexit DXCUPIDC should be executed for both fixed and pool.

3. SOLUTION CONSIDERATIONS:

4. KNOWN (PARTIAL) SOLUTIONS:

IBM Response

Currently USRPIDC is called if a long-term pool record ID is being changed on filing.
For long-term pool, ALCS can always compare the old and new record ID since the record was read into VFA if necessary before being filed.
For short-term pool and fixed file records, ALCS does not retrieve the old copy of the record if it was not in VFA before filing it.
If USRPIDC must be called for fixed file records as well as LT pool then there will be a potential, unpredictable overhead of reading fixed file records before filing.
To minimize this potential overhead, ALCS could check for USRPIDC (or a similar but separate exit) early in the file processing -- and if the exit is not loaded then avoid reading a fixed file record into VFA before filing.
We propose a new installation-wide monitor exit USRFIDC for fixed file record ID checking, with similar entry and return conditions to USRPIDC.

Users must be aware of the potential overhead of extra fixed file record reads when USRFIDC is loaded.