When running TMSXTEND,PARM=TEST I receive the TMSXT50I message to run TMSRINIT on all systems. Is this really needed during a TEST? Is there any possibility it would switch the TMC during the TEST?
Yes, you must run the TMSRINIT jobs as requested. During a TEST it will not switch the TMCs. If you don't run the TMSRINIT as requested the TMSXTEND,PARM=TEST will abend with a U1022-3B. During a TEST, the TMSRINIT is just checking that each CPU(LPAR) can see the TMC.N data set.