Online change and DEDB randomizer and exit routines

Randomizing routines determine the location of database records by AREA within the DEDB and by root anchor point (RAP) within the AREA. A change of the DEDB randomizer is a database level change.

A new randomizing routine affects the location (AREA and RAP) of every database record within the DEDB. The randomizer is defined for the DEDB in the DBD parameter: RMNAME=.

A randomizer change can involve introducing a brand new randomizer into the active IMS system or changing an existing randomizer in use by one or more DEDBs.

The name of the randomizer is specified in the DBD parameter: RMNAME=. If a new randomizer is introduced for an existing DEDB, a DBDGEN and ACBGEN of the database with the new randomizer name is required in addition to the following procedural steps.

To introduce a new DEDB randomizing routine using online change:

Procedure

  1. Use a specific customer-developed application program or original equipment manufacturer (OEM) utility to unload the DEDB with the current randomizer.
  2. Assemble and link edit the new randomizer into the IMS SDFSRESL or one of the libraries in the STEPLIB concatenation.
  3. Run a DBDGEN for the DEDB with the new randomizer designated in the DBD parameter: RMNAME=.
  4. ACBGEN is also needed to build the application control blocks to implement the DEDB definition that includes the new randomizer. The changed or new application control blocks must be built into the active IMS system's staging copy of ACBLIB, which is offline.
  5. Run the online change utility, DFSUOCU0, to move the changed ACBLIB from the staging ACBLIB to the inactive (A or B) copy of the ACBLIB that is online to the active IMS system.
  6. Remove access to the DEDB from the active IMS system and to unload the randomizer by entering the type-1 /DBR DB operator command sequence or the type-2 UPDATE DB STOP(ACCESS) operator command sequence. Do not use the OPTION(NORAND) parameter when you issue the UPDATE DB STOP(ACCESS) type-2 command, because the NORAND parameter prevents the randomizer from unloading.
  7. Enter and follow the online change command sequence for PREPARE processing for ACBLIB changes.
  8. Enter and follow the online change command sequence for COMMIT/ABORT processing for ACBLIB changes. The online IMS system will switch from using the active (A or B) copy of the ACBLIB to the inactive (A or B) copy.
  9. Delete, define and initialize all of the DEDB AREA data sets with the new system definitions.
  10. Make the DEDB and its areas accessible to the active IMS system by entering the type-1 commands /START DATABASE and /START AREA or the type-2 command UPDATE DB START(ACCESS) AREA(*).
  11. Use a specific customer-developed application program or OEM utility to reload the DEDB with the new randomizing routine in effect.