In current releases of VTAM®, a class-of-service (COS) name is associated with each logon mode name. See NIB LOGMODE and BNDAREA operands. When a logon mode name is specified with an Initiate request, SIMLOGON, REQSESS, OPNDST OPTCD=ACQUIRE, or CLSDST OPTCD=PASS, the COS name associated with that logon mode name is used by VTAM to establish the session.

The COS name is not returned to the application program when INQUIRE OPTCD=SESSPARM is issued.

A program that issues INQUIRE OPTCD=SESSPARM with a logon mode name to obtain a session parameter, and then use OPNDST OPTCD=ACQUIRE with a BIND image (pointed to by the BNDAREA of the NIB) built from those a session parameter gets the class of service associated with the default logon mode name. That class of service might not be the one that is associated with the logon mode name used by the INQUIRE macroinstruction. If this is undesirable, use SIMLOGON with the logon mode name specified in the NIB LOGMODE operand. The session parameter and COS name are presented to the program in the CINIT RU. Current releases of VTAM use the associated class of service when an OPNDST OPTCD=ACCEPT is issued.

A program that issues CLSDST OPTCD=PASS must also specify the logon mode name in the NIB LOGMODE operand, to ensure that the subsequent OPNDST OPTCD=ACCEPT uses the proper class of service. If CLSDST OPTCD=PASS is issued with LOGMODE=0, the COS name of the default logon mode name is used.