The Syntax for
Session data will vary, depending on how CICS signon transaction is configured. (CESN / CSSN etc..)
In this particular case, the following line command syntax was used to sign on to CICS using native VTAM (MSG10).
LOGON APPLID(CICSZ1A1) DATA('USERID=USERID1,PASSWORD=xxxxxxxx,FTRANS=')
or
LOGON APPLID(CICSZ1A1) DATA('USERID=USERID1,PASSWORD=xxxxxxxx')
This translates to the following specific syntax, required for the Session data, in this case.
Session Data : USERID=&USERID,PASSWORD=&PSWD (no quotes needed)