Database batch backout

Because it is possible (in an online IMS subsystem) to have more than one dependent region using the same PSB, the utility might back out changes from several dependent regions when you execute batch backout against an online log.

You can use the Batch Backout utility to back out changes to the last checkpoint a batch job did not complete normally. If the batch region does not use data sharing, and if it is not a BMP, you can use the CHKPT control statement on the JCL for the Batch Backout utility to back out changes for the batch region to any valid checkpoint, whether or not it completed normally. Do not specify the CHKPT control statement when backing out changes for BMPs; the utility either rejects or ignores it.

The Batch Backout utility reads the log in the forward direction. Regardless of whether the backout is to the last checkpoint or to a specified checkpoint, the utility tries to back out all changes to all databases occurring between that checkpoint and the end of the log. When backing out BMPs, the utility always backs them out to the last checkpoint on the log.

In an IMS DBCTL environment, the Batch Backout utility backs out all in-flight updates, but only backs out in-doubt updates if you specify the COLDSTART option.

If dynamic backout fails or if backout during emergency restart fails, IMS stops the databases for which backout did not complete, and retries the backouts when you restart the databases.