Both ACF2 and CICS have just been upgraded: CA ACF2 from v12 to v16; CICS TS from 2.3 to 4.2. Event Notification Facility (CAIENF) is running with the CICS component.
When ENF was enabled with "F ENF,MODE(CICS,NONE)" the abend is seen:
+DFHXS1103I CICSRGN Default security for userid user1 has been established.
IEA995I SYMPTOM DUMP OUTPUT 181
SYSTEM COMPLETION CODE=0C4 REASON CODE=0000003B
CA ACF2 for z/OS R16
z/OS 1.11 (confirmed)
CICS TS 4.2
CAIENF/CICS
In this case, a review of the dump reveals a back-leveled copy of ENF load module CAS9CICS.
This LMOD should be found in the CCS CAW0LOAD library.
Please check both linklist and ENF steplib for this module and make sure it matched your SMP/E installation target library