Enabling IMS management of ACBs in an IMS system that already uses the IMS catalog

If your IMS system is already configured to use the IMS catalog, you enable the IMS management of ACBs without having to enable the IMS catalog at the same time.

If you have recently migrated to a new release of IMS, make sure that the IMS system is stable and running with the IMS catalog enabled.

In data-sharing environments, evaluate the impact of enabling IMS-managed ACBs on your current configuration. If all IMS systems in the data-sharing group share a single IMS catalog, the effect of enabling the IMS management of ACBs is similar to having all IMS systems share a single ACB library.

Make sure that the ACB libraries that you provide as input to the IMS Catalog Populate utility (DFS3PU00) contain all of the ACBs that are currently active in the IMS system. The following catalog resources must be present in one of the ACB libraries:
  • DFSCD000
  • DFSCP000
  • DFSCP001
  • DFSCX000
  • DFSCPL00

Do not enable the IMS management of ACBs in the <CATALOG> section of the DFSDFxxx member until after the DFS3PU00 utility successfully creates the IMS directory and loads it with the active ACBs. If necessary, you can explicitly specify ACBMGMT=ACBLIB in the <CATALOG> section of the DFSDFxxx PROCLIB member until the IMS directory is ready to be used. IMS will issue message DFS7443E and terminate with a 0071 abend during IMS initialization if IMS managed ACBs is enabled and one or more of the following required catalog resources is not present in the directory: DFSCD000, DFSCP000, DFSCP001, DFSCX000 and DFSCPL00.

The default access level of the IMS catalog changes from ACCESS=READ to ACCESS=UPDATE when the IMS management of ACBs is enabled. You can specify the access level explicitly in the <CATALOG> section of the DFSDFxxx member or change it later by using the UPDATE DB or /START DB command.

Recommendations:

Keep the DBD and PSB source statements and the ACB, DBD, and PSB libraries intact until you are certain that you will not need to fall back to the use of installation-managed ACBs.

Similarly, do not delete from any JCL the DD statements that refer to the ACB, DBD, or PSB libraries until you are certain that you will not need to fall back.

If your IMS catalog is not already configured to use SMS-managed data sets, enable SMS-managed data sets now. The IMS catalog options for SMS-managed data sets are specified in the <CATALOG> section of the DFSDFxxx member.

To enable the IMS management of ACBs when you are already using the IMS catalog follow these steps:

  1. Optional: Specify a high-level qualifier for the IMS directory data sets on the SYSDSHLQ parameter in a CATDSHLQ DFSMDA macro statement.
    When the SYSDSHLQ parameter is not specified in the dynamic allocation macro (DFSMDA) statement, IMS derives the high-level qualifier for the directory data set, the boot strap data set, and the staging data set from the data set name prefix of the IMS catalog database data sets.
  2. Code the JCL and input control statements of the DFS3PU00 utility:
    • On the EXEC parameter in the JCL for the DFS3PU00 utility, specify PSB DFSCP001 for update access to the IMS catalog or, if you need to delete and reload the IMS catalog, you can use the load PSB, DFSCPL00, instead, which directs the DFS3PU00 utility to update the IMS catalog in load mode.
    • Specify one or more ACB libraries that contain the currently active ACBs by using the IMSACBnn DD statements.
    • Specify the MANAGEDACBS=SETUP control statement by using the SYSINP DD statement.
  3. Run the DFS3PU00 utility to set up the IMS catalog to manage ACBs. Make sure that you enabled the IMS catalog and specified the options for the IMS catalog as necessary in CATALOG and CATALOGxxxx sections of the DFSDFxxx member before using the DFS3PU00 utility. Set ACBMGMT=ACBLIB in the CATALOG and CATALOGxxxx section of the DFSDFxxx member until the IMS directory data sets are populated .
    The DFS3PU00 utility inserts any new or modified instances of DBDs or PSBs into the IMS catalog and loads all ACBs into the IMS directory data sets, which are IMS-managed system data sets that serve a similar purpose in the IMS system as the ACB library data sets. After an ACB is added to the IMS directory, the corresponding resources in the IMS catalog are flagged as active.
  4. For batch application programs, add the IMS catalog and ACB management definitions to the batch environment by either updating the execution JCL to reference the DFSDFxxx PROCLIB member or by using the IMS Catalog Definition exit routine (DFS3CDX0), which provides the definitions without requiring you to modify the JCL.
  5. In the <CATALOG> section of the DFSDFxxx member in the IMS.PROCLIB data set, specify ACBMGMT=CATALOG.
  6. Restart all IMS systems that use the DFSDFxxx member in which ACBMGMT=CATALOG is specified.
If you have utilities, tools, or processes that continue to require the ACB, DBD, and PSB libraries, the library members must match the resources that are flagged as active in the IMS catalog. To generate matching libraries after IMS is managing the ACBs, use the IMS Catalog Database Library utility (DFS3LU00).

Consider setting the CATALOG field of the RECON data set if you need DBRC to read DBD information from an IMS catalog registered with DBRC. You can set the CATALOG field by using the CHANGE.RECON command. If you do not specify the field, DBRC reads DBD information from the DBDLIB. For more information, see DBRC access to DBD information when IMS manages ACBs.