IMS™ management of ACBs

This topic describes how FM/IMS operates when IMS™ is configured to manage the runtime application control blocks (ACBs).

When management of ACBs by IMS™ is enabled:

  • The IMS™ catalog is the trusted source for DBDs and PSBs.
  • IMS™ mostly no longer requires DBD, PSB, and ACB libraries.

In keeping with this, FM/IMS retrieves the PSBs and DBDs from the IMS catalog.

The IMS Catalog API (DFS3CATQ) is used to retrieve these control blocks.

Restriction: FM/IMS does not support accessing logical databases, as the IMS Catalog API does not support retrieval of logical DBDs.

Configuring FM/IMS when IMS™ management of ACBs is enabled

Set ACBMGMT=CATALOG on the FMN1POPI macro statement to specify that IMS™ management of ACBs is enabled.

Also set the following FMN1POPI parameters:

  • Use the BSDSHLQ parameter to specify the high level qualifier for the IMS™ bootstrap data set.
  • Use the DFSDF parameter to specify the 3-character suffix of the DFSDFxxx member of the IMS™ PROCLIB data set that contains the settings and attributes of the IMS™ catalog.
  • Use the PROCLIB parameter to specify the name of the IMS™ PROCLIB data set that contains the required DFSDFxxx member.
  • Use the REGCATLG parameter to specify whether the IMS catalog is registered with DBRC.

For more information on how to code these parameters, see FM/IMS options.

Note: The DBDLIBn, DBRC, and PSBLIBn parameters are not used when IMS management of ACBs is enabled.

Dynamic PSB support when IMS™ management of ACBs is enabled

Dynamic PSBs are supported differently when IMS management of ACBs is enabled.

When USEDDL is set to Y on the FMN1POPI macro statement, dynamic PSBs are generated by submitting Data Definition Language (DDL) SQL statements to the IMS Data Definition utility (DFS3ID00). When they are no longer required, they are deleted in the same way — by submitting DDL SQL statements to the IMS Data Definition utility.

Prerequisites: Support for running the IMS Data Definition utility in a BMP region was delivered with APAR PH45367/PTF UI81894 and enabled by IMS 15.3. Support for running it in a DL/I batch region was delivered with APAR PH51761/PTF UI91330 and enabled by IMS 15.4. Ensure you are at or above these levels to generate and delete dynamic PSBs this way.

When USEDDL is set to N on the FMN1POPI macro statement, FM/IMS generates dynamic PSBs by submitting macro instructions to the PSB generation utility and then uses the ACB Maintenance utility and the IMS Catalog Populate utility (DFS3PU00) to add the PSB to the IMS catalog. However, this method of generating dynamic PSBs has been deprecated, so using it is not recommended.

For more information on how dynamic PSBs are generated when IMS management of ACBs is enabled, see USEDDL.