Session limit negotiation is the process by which two parallel-session-capable LUs determine the session limits for a logon mode group before they establish a session on that logon mode. (Session limits are not negotiated for single-session-capable LUs.) These session limits define the type and number of sessions in use between the two LUs. The logon mode is associated with specific characteristics, such as class of service, which describe its communication capabilities, and is represented by a logon mode name.
To initiate session limit negotiation, either the local LU or the partner LU issues the APPCCMD CONTROL=OPRCNTL, QUALIFY=CNOS macroinstruction. The LU that initiates the CNOS request is the source side, and the partner LU is the target side.
VTAM® performs the session limit negotiation.