When you complete a logical message with a disposition of PAGING, BMS arranges to deliver the entire logical message, which it has accumulated in temporary storage. The display or printing of pages can be done inline, immediately after the SEND PAGE command, but it is more common to schedule a separate task for the purpose. In either case, CICS® supplies the programs required. These programs allow a terminal operator to control the display of the message, paging back and forth, displaying particular pages, and so on. When a separate task is used, it executes pseudoconversationally under transaction code CSPG. When the display is inline, the work is done (by the same CICS-supplied programs) within the task that created the message, which becomes conversational as a result.
You indicate how and when the message is sent by specifying RETAIN, RELEASE, or neither on your SEND PAGE command. The most common choice, and the default, is neither. It causes CICS to schedule the CICS-supplied transaction CSPG to display the message and then return control to the task. The CSPG transaction is queued with any others waiting to be executed at your terminal, which execute in priority sequence as the terminal becomes free. In the ordinary case, where no other tasks waiting, CSPG executes as soon as the creating task ends.
The RELEASE option works similarly, but your task does not regain control after SEND PAGE RELEASE. Instead, BMS sends the first page of the message to the terminal immediately. It then ends your task, as if a CICS RETURN had been executed in the highest level program, and starts a CSPG transaction at your terminal so that the operator can display the rest of the pages. The CSPG code executes pseudoconversationally, just as it does if you specify neither RELEASE nor RETAIN, and the original task remains pseudoconversational if it was previously.
There are two other distinctions between RELEASE and using neither option:
SEND PAGE RETAIN causes BMS to send the message immediately. When this process is complete, your task resumes control immediately after the SEND PAGE command. When the terminal is a display, BMS provides the same operator facilities for paging through the message as the CSPG transaction does, but within the framework of your task. The code that BMS uses for this purpose issues RECEIVE commands to get the operator’s display requests, and this causes your task to become conversational.