Queuing messages to a multi-access SPOOL node

Optionally, you can direct commands and messages to a particular JES2 member attached to the spool. Use $NnnnMmm to route a command to a specific member, where mm is the member number as defined on the MEMBER(mm) statement.

The MASMSG= parameter on the CONDEF statement specifies the maximum number of commands or messages that can queue between any two members of the multi-access spool configuration before the network discards messages. This count also applies to the number of input messages or commands a member can queue to itself.

When a member of a multi-access spool node queues a message to another member of that node, there is no interrupt mechanism to inform the receiving member that a message exists. The receiving member periodically reads the shared job queue record and examines queue information for new messages. The following JES2 initialization parameters control the length of time it takes for the receiving member to recognize the queuing. You specify the parameters (HOLD= and DORMANCY=) on the MASDEF initialization statement, and specify (DELAY=) on the NJEDEF statement. The $T operator command can modify each of these parameters to make it easier to tune your multi-access spool node.

You should experiment to determine the parameter values that yield satisfactory responsiveness without causing adverse increases in system overhead for the individual nodes. Figure 1 shows examples of these parameters. These values are for illustrative purposes and are not recommendations.