P processing option
If the P processing option is specified in the PCB for your program, a GC status code is returned to your program whenever a call to retrieve or insert a segment causes a unit of work (UOW) boundary to be crossed.
Related reading: For more information on the UOW for DEDBs, see IMS Version 15.2 Database Administration.
Although crossing the UOW boundary probably has no particular significance for your
program, the GC status code indicates that this is a good time to issue either a
SYNC or CHKP call. The advantages of issuing a
SYNC or CHKP call after your program receives a GC status code
are:
- Your position in the database is retained. Issuing a
SYNCorCHKPcall normally causes position in the database to be lost, and the application program must reestablish position before it can resume processing. - Commit points occur at regular intervals.
When a GC status code is returned, no data is retrieved or inserted. In your program, you can either:
- Issue a
SYNCorCHKPcall, and resume database processing by reissuing the call that caused the GC status code. - Ignore the GC status code, and resume database processing by reissuing the call that caused the status code.