Question:
Does TPX have any issues with the setting ALLOWUSERKEYCSA(NO) in member DIAGxx of SYS1.PARMLIB?
Answer:
With ALLOWUSERKEYCSA(NO) it will depend upon how you have SRBEXIT defined in your VTAM members.
If TPX is configured to run with SRBEXIT=YES in VTAM Major Node Member, ALLOWUSERKEYCSA(NO) will keep TPX from allocating CSA in user keys and should not be a problem.
If instead SRBEXIT=NO is specified in the VTAM Major Node Member, ALLOWUSERKEYCSA(NO) prevents user key CSA from being allocated by failing any attempt to obtain user key from a CSA subpool (through GETMAIN or STORAGE|OBTAIN) with a B04-5C, B0A-5C, or B78-5C abend.