DBRC fallback considerations

Certain steps must be taken to revert the level of DBRC from IMS 15 to IMS Version 13 or IMS 14.

Minimum version value in the RECON data set

If the MINVERS value is set to '15.1' and you need to fall back from IMS 15 to an earlier version, you must lower the MINVERS value because jobs in an earlier release cannot access the RECON data if the current MINVERS value is set to '15.1'.

To change the MINVERS value to '13.1', complete the following steps:
  1. Shut down all IMS 15 subsystems.
  2. Ensure that all IMS 15 subsystem records have been removed from the RECON data set. Issue a LIST.SUBSYS command to see the subsystem records in the RECON data set. Delete all IMS 15 subsystem records in the RECON data set using the DELETE.SUBSYS command.
  3. If the cross-DBRC service level ID (CDSLID) is not set to 2 and any HALDB databases are defined to support 8-GB OSAM data sets, the CHANGE.RECON MINVERS('13.1') command will fail, and message DSP1256E will be issued. To prevent the command from failing, take one of the following actions:
    • Complete the appropriate steps to change the maximum OSAM data set size for each HALDB from 8 GB to 4 GB.
    • If the appropriate maintenance for HALDB support of 8-GB OSAM data sets has been applied to all of the IMS Version 13 resident libraries (RESLIBs) that access the RECON data set, include the CDSLID(2) parameter in the CHANGE.RECON MINVERS('13.1') command in the next step.
  4. Reset the MINVERS value by issuing a CHANGE.RECON MINVERS('13.1') command using IMS 15.

To change the MINVERS value to '14.1', complete the following steps:

  1. Shut down all IMS 15 subsystems.
  2. Ensure that all IMS 15 subsystem records are removed from the RECON data set.
    • To view the subsystem records in the RECON data set, issue the LIST.SUBSYS command.
    • If IMS 15 subsystem records exist, issue the DELETE.SUBSYS command to delete them.
  3. Issue the CHANGE.RECON MINVERS('14.1') command to reset the MINVERS value to fall back to IMS 14 from IMS 15.