Falling back from IMS-managed ACBs before resource updates are activated

If your installation has not activated any new or modified databases or program views since enabling the IMS management of ACBs and your ACB, DBD, and PSB libraries are unchanged, the procedure for falling back from the IMS management of ACBs to the installation-managed ACB libraries (ACBLIBs) involves updating the DFSDFxxx member, changing various references to the IMS catalog back to references to the ACB, DBD, and PSB libraries, and restarting IMS.

The following procedure does not include steps for falling back from an IMS catalog. Disabling the IMS catalog is not required when falling back to installation-managed ACBLIBs.

The following procedure is generally applicable to both falling back within a release and falling back to a prior release of IMS.

Procedure

  1. In the <CATALOG> section of the DFSDFxxx PROCLIB member, specify ACBMGMT=ACBLIB.
  2. If you use the IMS Catalog Definition exit routine (DFS3CDX0), modify it to indicate that the IMS management of ACBs is not enabled.
  3. If necessary, update any JCL to reference the ACBLIB, DBDLIB, and PSBLIB.
  4. If DBRC was configured to refer to the IMS catalog for database definitions, reconfigure DBRC to refer to the DBDLIB instead by issuing the CHANGE.RECON command with NOCATALG specified.
  5. Restart IMS.

Before running the IMS Catalog Populate utility (DFS3PU00) again on a system that uses ACB libraries, remove the MANAGEDACBS control statement from the JCL.

If necessary, revert any tools or products that were updated to run in the IMS-managed ACBs environment so that they use the ACB, DBD, and PSB libraries again.