Configuring the z/OS TN3270E Telnet server (two-tier solution)
Express Logon Feature requires TLS/SSL with level 2 client authentication functionality at the server. After that level of security is working, specify the EXPRESSLOGONMFA (to use Multi-Factor Authentication tokens) or EXPRESSLOGON (to use PassTickets) parameter statement to enable ELF in the z/OS® TN3270E Telnet server.