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Designing and Programming CICS Applications by Members of the CICS Development Team at IBM Hursley, John Horswill

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Chapter 11. Programming the 3270 Presentation Logic Component

In this chapter:

There are three steps that are necessary to build up this component:

  • Defining screens using Basic Mapping Support (BMS)

  • Sending and receiving data (NACT01)

  • Local printing (NACT03)

Part way through the chapter, we’ll have a digression and introduce a little background about symbolic description maps.

First, a recap about the purpose of the component that we are going to write. This program is the first one executed when the NACT transaction is entered on a 3270 terminal. Apart from local printing, all of the code in the presentation logic has been placed in a single program. This is because the application is not big enough to justify multiple programs. NACT01, the name of our program, displays the menu screen, which prompts the user for request input, and ends when it returns control to CICS. In returning, it specifies that the same transaction (NACT) is to be executed when the next input is received from this terminal. NACT01 will be invoked repeatedly to process the input from the menu. A typical piece of code that does this is:

X-RETURN-COM-AREA SECTION. * * This routine saves data and ends the task * * This section is performed from the following sections - * B-GET-MENU-DATA * DB-SEND-DETAIL-WITH MESSAGE * DE-SEND-MENU-WITH-MESSAGE * U-SEND-EMPTY-MENU ...

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