Online change and HALDB alter

If you use ACB libraries, the IMS online change function is required to enable access to the new structure of a HALDB database after alter processing completes.

If you are altering a HALDB database in an IMS-managed ACBs environment, instead of using the online change function, you must issue the IMPORT DEFN SOURCE(CATALOG) command after alter processing completes to enable access to the new structure of the database.

In addition to activating the ACB members that contain the new database structure, the online change function clears various flags and counters in the RECON data set. Activating the ACB members by a means other than the online change function does not clear the flags and counters automatically.

Until the ACB members are activated and the flags and counters are cleared, the alter procedure is not complete and the new database structure cannot be used.

Before you start the online change procedure to complete an alter operation, you must stop access to the HALDB database by issuing either a /DBRECOVERY DB HALDB_master_name command or an UPDATE DB NAME(HALDB_master_name) STOP(ACCESS) command.

If you use ACB libraries, use the member online change function to complete the alter procedure. The member online change function reads directly from the staging ACB library and can process only the specific ACB members that require activation. The local and global online change functions require you to copy the ACB members into the inactive ACB library. They also process the entire ACB library, instead of just the ACB members that contain the new database changes.

In a data sharing environment that uses ACB libraries, if you use local online change you must coordinate it across all IMS systems that share the database. Because the first IMS system in which the local online change is performed resets all of the flags and counters in the RECON data set, you should issue the /DBRECOVER command for the database in all IMS systems first and then do the local online change in each system.