After upgrading from z/OS 1.13 to z/OS 2.1, CICS 5.3 receives the following message at startup.
DFHDM0105 cicsjob Unsuccessful initialization of DFHUS domain. CICS will terminate.
The CICS region gets phase 0 started and completed, but not phase 1 or 2.
ENF was up completely at the time the CICS region was started.
TSSUTIL shows a 1C-03 message for acid *MISSING in the CICS region. The check comes from program DFHKETCB.
CICSREL(70) is coded in the ENF parameters.
Neither the CICS region acid or the CICS default user id are suspended.
Check the KERBEROSUSER= parameter in the CICS System Initialization Table (SIT). This is a new parameter that was introduced after the initial release of CICS/TS 5.3. If the SIT has no entry for this parameter, set KERBEROSUSER= to the CICS region ACID in the CICS SIT or the SYSIN startup that overrides the SIT.
There is nothing that is needed on the CA Top Secret/CICS side relating to KERBEROS. If a valid acid is passed on SIT option KERBEROSUSER=, then CA Top Secret will simply signon that ACID.
Also look at IBM APAR/PTF PI96603/UI56167 that may be related to this error. This APAR was opened against CICS/TS 5.4.