TN3270 changes
In TelnetParms, add the lines in red: 
TelnetParms

;     DEBUG TRACE JOBLOG

      SECUREPORT 993

      KEYRING SAF  RACF keyring name

      ENCRYPTION DEFAULT ENDENCRYPTION

      EXPRESSLOGON

      CLIENTAUTH SAFCERT

      CONNTYPE ANY

      SSLTIMEOUT 120

      NOSEQUENTIALLU

EndTelnetParms
Note
For more information, refer to the following IBM publications:
•  APPENDIX1.3 Appendix C - Express Logon Feature
•  z/OS V1R9.0 Comm Svr: IP Configuration Reference
Related Links
Express logon feature (Parent Topic)