The DEBUG facility can be used to trap incorrect alterations of checkpoint data (using DEBUG=Y|N), and it can be used (if additional parameters are included with the command) to record certain JES2 events and activities. For example, you can specify whether to count certain events, provide certain $HASP095 error information to the operator, verify the integrity of a newly created checkpoint version, or, start or stop monitoring updates made to the checkpoint data set. The information collected from the monitoring can be made available through a dump of the JES2 address space.