Processing Commands

The AST task processes the FORCE, ITO, and RETRY commands for auto-start links. These commands are represented by the Type C0, Type C1, and Type C2 formats, respectively, of the CMNDAREA.

If a FORCE command is issued for a link that was attached from the AST task, the REX task passes the command to the AST task. This enables the AST task, which attached the link driver task, to detach and terminate the link.

The ITO command, an internal RSCS command element, is enqueued to the AST task by any link that has been defined with a nonzero ITO interval. When a link initializes, it enrolls itself into the ITO process. The link driver task then resets the inactivity time-out value in its LINKTABL when it executes an open request for an input or output file. The AST task monitors the ITO value to determine if the link should be deactivated.

The RETRY command, another internal RSCS command element, is enqueued to the AST task by the end-of-task routine (DMTMANEX). The AST task receives this command element when an SNA or auto-dial link deactivates with an error condition that makes it eligible for a retry. The AST task monitors the number of consecutive retry attempts on the link. It then copies the appropriate retry interval in to the link’s LINKTABL entry. The AST task then attempts to start the link after the retry interval expires. The retry intervals default to 1, 10, 19, 27, 34, 40, 45, 49, 52, 54, and 55 minutes. These values can be overridden by the RETRY statement, described in z/VM: RSCS Networking Planning and Configuration.