https://www.ibm.com/docs/en/ims/15.6.0?topic=systems-synchronization-point-processing-physical-logging
IMS 15.6 - Database administration - Synchronization point processing and physical logging
Some 'clustering' of output and release of updated CIs and buffers occurs because DEDB updates are deferred until after physical logging is complete.
15 6database administrationsynchronization pointims