This document details one type of failure/corrective action, when the MSM/MUF fails with ABEND=S000 U0004 REASON=00000000.
Review the output (through SDSF, Sysview, etc...) from the MSM MUF startup. Look to determine whether the following message was generated.
+DB00121I - UNAVAILABLE - MF20MSM
The above message is an indication that another CA Datacom/CA Mainframe Software Manager MUF instance is active with the same name (MF20MSM).
Review the MSMSetupOptionsFile.properties options file. The CA Datacom/CA Mainframe Software Manager Multi-User Facility name must be unique. The default value is MF20MSM. Reinstall CA Mainframe Software Manager, ensuring the CA Datacom/CA Mainframe Software Manager MUF name is unique.
If the above process does not address your specific problem, please contact Support.