DFHFCCA (file control RLS control ACB manager)

DFHFCCA is the file control RLS control ACB manager. The RLS control ACB is a special ACB required when a commit protocol application such as CICS uses VSAM RLS. FCCA processes requests to register and unregister the control ACB, and all other file control requests to SMSVSAM that have to be made via the control ACB. These requests are:
  • IDAREGP (register)
  • IDAUNRP (unregister)
  • IDARECOV (clear recovery status)
  • IDAINQRC (inquire on recovery)
  • IDAQUIES (quiesce)
  • IDALKREL (release locks, and retain locks marked for retention)
  • IDARETLK (mark locks for retention)

DFHFCCA also includes the code for the RLSWAIT exit used by control ACB requests. Whenever CICS issues such a request, VSAM drives the RLSWAIT exit as soon as it is about to transfer control to the SMSVSAM address space. CICS is then able to drive the dispatcher and schedule other CICS tasks whilst the SMSVSAM address space is busy processing the request.