Logon Address Space (LAS) functions

The following considerations apply:

• VTAM must be available and the Alternate Access VTAM application major node must be active before the LAS can be started (see Activating-the-VTAM-application-major-node for more information).
• The address space for the LAS must run as a started task and can be started by an operator or during IPL (see Starting-and-stopping-the-logon-address-space-LAS for more information).
• The startup procedure (proc) for the LAS must be placed in a JES-defined data set, such as SYS1.PROCLIB, that is referenced by started tasks.
• Only one LAS needs to run per system; other LASs can run but must be named uniquely (see Starting-and-stopping-the-logon-address-space-LAS for more information).
• The LAS should stay active at all times; otherwise, VTAM terminal users cannot log on.
• The LAS acknowledges the LOGON command (see Using-the-LOGON-command for more information) or an abbreviated logon command that has been customized to your site’s USS table or logon interpret table (see Using-the-abbreviated-logon-command for more information).

When active, the LAS requests the user ID for a terminal session and issues a START command containing the user ID to initiate a TAS. After a TAS is initialized, it becomes independent of the LAS, so the LAS is not a single point of control (or failure) for a user session. Specifically, the sequence of events that occurs in association with the LAS is shown in here.