Spooled output control

You need to be aware of requirements for IMS spooled output. This is because the output might be needed immediately by the end user or additional output can be impeded if allocated space is exhausted.

Given a spool line group, you need to be aware of how many data sets are used for output. A recommended definition is at least two data sets, one data set printing while the other receives additional input. The line number and PTERM references are also required.

At any time, you can use the /STOP LINE n PTERM nn command to call for the spooled output to be scheduled to a printer.

The action of this command is to close the data set and direct additional output to the next spool data set. If this is the last in the set, output goes to the first. If only one output data set exists at the time the print utility is scheduled, all messages for the LTERM are queued. This could rapidly add to the contents of the message queues. Message queues can fill very quickly, specially when the spool is the secondary master console. The IMSWTnnn procedure to execute the print utility is scheduled automatically by the data-set-full condition. A write error for the data set also starts the procedure.

The printing procedure is tailored to the line group data sets by system definition. You can invoke this procedure at any time by using a /START REGION IMSWTnnn command. If the data sets are not closed, current line output is queued.

Restart can affect spooled output handling. If output data sets were not printed from a prior execution, the /NRESTART command prevents additional output messages. The action of a /START LINE automatically schedules the IMSWTnnn procedure and frees the data set for output from the current system execution.