312 IBM IMS Version 12 Technical Overview
For each IMS that you are falling back, complete the following steps:
1. Ensure that the status of all databases updated by IMS 12 is correct.
Establish a new recovery point for these databases by image copying them before
allowing updates in the fallback release.
2. Resolve DBRC issues. See 8.7.4, “DBRC fallback considerations” on page 312.
Make sure you have the correct DBRC Coexistence PTF applied to the older IMS
(PK61583 and PK61582).
3. Shut down IMS 12.
4. Install the old version of IMS.
You must rebuild your ACB library at the IMS version to which you are falling back.
5. Restart IMS.
You can use the IBM IMS Queue Control Facility for z/OS (QCF) to requeue IMS 12
messages to IMS 10 or IMS 11 message ...