The CMGRMON task took a dump and terminated with CMGR644E,CMGR Change Monitor SQL ERROR SQLCODE: FFFFFC64 SQLERRM: 0001.0100.00F30805. What causes this?
The reason code included in the error message CMGR644E indicates the DB2 subsystem has terminated or is in the process of terminating, and without the DB2 backend the monitor cannot continue to run. Here is the IBM definition of the reason code:
The caller's connection with DB2 has been terminated, because the DB2
subsystem has terminated or is in the process of terminating abnormally.
The request may have been processed or aborted.
The requester may identify to DB2 when it becomes operational again.
As of now CMGR processing does not have the type of recovery where it can either automatically switch to another sub system in a DB2 sharing group or recognize the restart of DB2 and auto connect. That capability is in the planning stages for future enhancements to CMGR, for now sites should just restart the CMGR monitor after DB2 is once again available and it should be successful.