IMS and CQS should manage the case when MSGQ Messages could be found to be "in-doubt" at IMS CQS Restart + Structure Rebuild

There is a case, as per original Shared Queues design, when even during a Warm (not Cold) Restart MSGQ Messages can be found to be "in-doubt" so that CQS as a safe and conservative choice move them to the Cold Queue, where they would remain forever waiting for Customer decision about what to do with them (Unlock or Delete).
This is the situation where IMS and CQS are Warm Restarted and also MSGQ Structure is being rebuilt (e.g. in DR remote site) after LPAR(s) failure, and this would involve MSGQ Messages that were Locked (e.g. being processed) at that time.
To perform the Structure Rebuild the CQS Log Records are used, but, as per design, some could have been lost as a conseguence of the original LPAR failure because CQS was not able to write out to the Logstream the Log Records that it was batching in the Buffer (for performance reason).
Missing of the necessary TYPE0D "Delete" CQS Log Records would cause CQS not to be able to decide if a MSGQ Message should be unlocked or deleted at Restart + Structure Rebuild.
It is necessary IMS and CQS could perform the necessary "reconciliation" from the IMS Log necessary to understand if those MSGQ Messages should be be Unlocked or Deleted. This could require IMS / CQS to go back further than the Restart Checkpoint (i.e., suppose you had a slowly-running IMS, such that some of the 33 records you needed to understand if a message was deleted were back before the restart checkpoint).

Opened on behalf of Banca d'Italia - BdI Customer.