Predefined LU and LOGON

With predefined LU and LOGON, you can bypass the SMCS selection screen by indicating that a particular console name is always associated with a particular LU. Once the LU is logged on to the SMCS application, the console becomes active.

The LOGAPPL VTAM® function indicates that a particular LU automatically logs on to a particular application when the LU becomes active. By indicating that a particular LU automatically logs on to the SMCS application with LOGAPPL, and indicating that the LU is associated with a particular console name with a predefined LU, a console can be activated automatically once VTAM is active, in much the same way that MCS consoles activate automatically during IPL.

The predefined LU allows an SMCS console to activate at one particular LU. To specify a predefined LU, specify the LU keyword on the CONSOLE statement. If a predefined LU is specified for a console, only that console can be activated at that LU. No other console can be activated at that LU, and that console can only be activated at that LU. The predefined LU can be changed later with the VARY CN command.

SMCS consoles also support the LOGON keyword on the CONSOLE statement. This keyword allows the console to override the LOGON value on the DEFAULT statement. However, some of the definition and operation of LOGON for SMCS is different than MCS and also depends on whether or not a predefined LU is specified.

If a predefined LU is specified, the LOGON definitions are the same as for MCS consoles:

LOGON (OPTIONAL) indicates that the console does not need to be logged on.
LOGON (AUTO) indicates that the console is automatically logged on.
LOGON (REQUIRED) indicates that the console must be logged on before commands can be issued.
LOGON (DEFAULT) indicates that the console is to use the LOGON value specified on the DEFAULT statement.
If LOGON is not specified, the console also uses the LOGON value specified on the DEFAULT statement.

If a predefined LU is not specified:

LOGON(OPTIONAL), LOGON(AUTO), LOGON(REQUIRED), and LOGON(DEFAULT) work the same as if a predefined LU was specified.LOGON(REQUIRED) is, however, strongly recommended.
If LOGON is not specified, the console default is LOGON(REQUIRED). The console does not use the LOGON value specified on the DEFAULT statement.
Regardless of whether a predefined LU is specified or not, LOGON is different for MCS and SMCS consoles. An MCS console always displays all messages that it receives; the console does not have to be logged on by an operator to receive messages. An SMCS console, in contrast, always displays messages explicitly queued directly to it. However, to display all messages that it normally receives, the console must be defined with LOGON(OPTIONAL), either by default or because it was specifically indicated, or it must be logged on by an operator.