At CTS 6.1, transaction CSSF is not longer valid.
Should the ACF2PARM members changed to reflect CESN/CESF instead of the CSSF/CSSN?
Release : 16.0
CESF and CESN are the appropriate signoff and signon transactions to specify in the ACF2PARM member.
Your user's will need to be made aware of the IBM change to the signon and signoff transaction names.