The $DEMO job runs properly when executing with the active load library being used in the LNKLST. The SOC1 on the FCOIEXT step occurs when using a STEPLIB to another load library that is not in the LNKLST. Typically, the STEPLIB has some newly applied maintenance and is being used for testing only.
You cannot add a STEPLIB for the new load library to the $DEMO job and execute the job without the S0C1 occurring. In order to run with a STEPLIB to different modules, you need to start a test CA PDSMAN address space that has the same STEPLIB DD statement. Then you can submit the $DEMO job and it will complete normally.
Note: You will see the following messages in the PDSM19 report:
WARNING - PDSMCM1 LIBRARY/RESIDENT MODULE MAINTENANCE INCONSISTENT