Altering the definition of an online DEDB database with the DEDB Alter utility

You can alter the database or area definitions of a DEDB database that uses a two-stage randomizer (or a one-stage randomizer for a DEDB database with only one area) with the DEDB Alter utility (DBFUDA00) while the DEDB area or the DEDB database remains accessible online.

If you are to use the DEDB Alter utility, set ALTERHLQ as the default in the Fast Path section of the DFSDFxxx member of the PROCLIB data set.

If more than one IMS is involved, you must set ALTERGRP in the Fast Path section of the DFSDFxxx member of the PROCLIB data set.

If you enable ACB libraries by specifying ACBMGMT=ACBLIB in the DFSDFxxx member of the IMS PROCLIB data set, the DEDB Alter utility supports both FDBR and XRF for ACBSHR=Y and ACBSHR=N.

If you enable IMS to manage ACBs by specifying ACBMGMT=CATALOG in the DFSDFxxx member, the DEDB Alter utility supports IMS-managed ACBs for both ACBSHR=Y and ACBSHR=N. When IMS manages ACBs, the DEDB Alter utility supports only FDBR.

Restriction: Because the IMS management of ACBs does not support XRF environments, the DEDB Alter utility does not support XRF when IMS manages ACBs.

If you use ACB libraries and the DEDB Alter utility successfully alters the definition of an online DEDB database, the DEDB definition that was used to alter the DEDB remains in the staging ACB library data set. If you use IMS managed ACBs, the DEDB definition is deleted from the IMS staging directory after the DEDB Alter utility successfully completes. If IMS manages ACBs and the DEDB Alter utility fails, pending DEDB definitions remain in the IMS catalog and you do not need to prepare the DEDB definition in the IMS catalog.

Requirements:
  • The randomizer must either be a genuine two-stage randomizer defined as one in the DBD or, optionally, a one-stage randomizer defined as one in the DBD, if the DEDB has only one area.
  • All IMS data sharing systems must be at IMS 15 or later.
  • The DEDB databases must be registered to DBRC.
  • If you are using the DEDB Alter utility to add a Segment Edit/Compression exit routine, the Segment Edit/Compression exit routine must be able to handle mixed compressed and non-compressed data in a DEDB database. If data is non-compressed, on read access, it does not expand the non-compressed data, and on write access, it compresses the data and writes out as compressed data. If data is compressed, on read access, it expands the compressed data, and on write access, it compresses the data and writes out as compressed data.
  • if you expand just the SDEP portion of an area by increasing the shadow’s data set size, you will still need to do an ACBGEN.

The DEDB Alter function supports both single and multiple area data sets (ADS). You have control over the output of the DEDB Alter function as either single or multiple ADSs depending on the number of shadow area data sets that you define to DBRC for the DEDB database.

The DEDB Alter function does not support DEDB databases that are in Fast Path Virtual Storage Option (VSO) or Shared Virtual Storage Option (SVSO) mode. DEDB databases using the VSO or SVSO option must first be unloaded to DASD using the /VUNLOAD command before running the DEDB Alter utility.