TERMINAL PAGING - IBM Mainframe

Terminal paging means creating a multi-page output message - with or without using page building. The terminal user can then page through the message under control of a BMS task rather than your application program. Terminal paging is often used in conjunction with file browsing, when more records are retrieved than can be displayed on one page.

Message Larger than a Page

Message Larger than a Page

The display shown in the above figure illustrates a case where the message is more than one page. As the program builds the pages for display, BMS saves the pages in CICS temporary storage until the output message is complete. BMS then transmit the pages to the terminal, page-by-page, under the Ser's control. When you send a set of pages to a destination terminal the output pages are collectively known as a logical message. A logical message is similar to a batch report consisting of multiple pages. Each page contains common information at the top and the bottom; the body of the page, contains the variable data. This process is shown in the following figure.

If the logical message created for an interface device such as 3270 display, the terminal user can retrieve and display the pages individually.

The user requests each page by keying in a paging command that is recognized and interpreted by CICS. Paging Commands are defined by the installation, according to the installation standards and application requirements. When the user enters the screen and CICS detects the presence of a paging command in the terminal input, the CICS supplied paging transaction is initiated to display the page at the terminal. By entering the appropriate paging command, the terminal user can request BMS to display the first or last page, display next or previous page or display a specific page.

For the terminal user's convenience, you will usually reserve a field in the map for entry of the paging command. This field is typically initialized to a default command, usually the next page command. An installation can also define the 3270 PF keys to be interpreted as paging commands say PF7 for previous page and PF8 for next page. That is instead of entering a paging command on the screen the user just has to press the PF key to display a page. This process is called Single Keystroke Retrieval (SKR).

Logical Messaging

Logical Messaging

Displaying a Logical Message

Displaying a Logical Message

You can elect not to send the formatted logical messages to the terminal by coding the SET option in the SEND MAP and SEND PAGE commands. When you specify the SET option, BMS returns the pages to your application program rather than scheduling the paging transaction to send the output to the terminal. Your program can then manipulate the pages and do the actual output with a SEND TEXT command. You might choose this method if you wish to implement your own paging scheme rather than the CICS terminal paging facility.

The application program has the option of deleting the logical message from the temporary storage before the message is delivered to the terminal by the PURGE MESSAGE command and this command can be used for exception handling.


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