Online changes in managed-ACB environments

When the IMS management of ACBs is enabled, you use the IMPORT DEFN SOURCE(CATALOG) command to change the active ACBs in online IMS systems. You cannot use the online change function to activate ACBs when they are managed by IMS.

The ACBs that contain the pending changes must be in the staging data set of the IMS catalog before you issue the IMPORT DEFN SOURCE(CATALOG) command.

When the IMPORT DEFN SOURCE(CATALOG) command is issued, IMS takes the following actions:
  1. Adds or replaces the ACBs in the directory data set of the IMS catalog.
  2. Removes the ACBs from the staging data set of the IMS catalog.
  3. Removes all old copies of the resources from memory and casts out DMBs and PSBs from their respective pools.
  4. If the IMS catalog is shared by multiple IMS systems, coordinates the change across the IMSplex.
  5. Updates the IMS catalog HEADER segment for the imported objects.

When you issue the IMPORT DEFN SOURCE(CATALOG) command, IMS uses an internal process that is similar to the online change function to activate the resources in online IMS systems. Consequently, if you issue the QUERY MEMBER command during import processing, the status reflects the same prepare and commit phases that online change uses. If errors occur, the messages might also reflect these phases.

Depending on the type change you are making and whether you are updating PSBs, DBDs, or both, you might need to take more steps before the resources can be used. For example, you might need to reorganize the database for certain types of database changes, or you might need to allocate data sets, register the database with DBRC, or issue the IMS type-2 CREATE DB command if you are creating a new database.