Can I change the MVSHFSDsnPrefix HLQ specified in the MSMSetupOptionsFile.properties without having to reinstall the CA-CSM?
Yes, the MVSHFSDsnPrefix parameter in the MSMSetupOptionsFile.properties file is the equivalent to mpmHlq in SAMPLIB(DBINIT) .
Go into SAMPLIB(DBINIT) and update mpmHlq.to have the new HLQ. Shutdowm MSMTC and temporarily change the //DBINIT DD to //DBUPDATE in the MSMTC startup JCL/PROC and start MSMTC.
Note that this change is not retroactive. Only new file systems will have the new HLQ. To change them all will involve updating the MOUNTPOINT table.