A simple example can be used to explain the consequences
of different application design techniques.
Figure 1 shows how CICS MAPs and transaction IDs are correlated, and how the
transactions work, without Db2® considerations. Figure 1. Example of a typical application design
In this example:
The transaction ID, TRX0, is specified in the EXEC CICS RETURN TRANSID(TRX0) command, when a
program (not shown) returns control after displaying MAP0.
The next transaction then uses the transaction ID, TRX0, independent of what the terminal user
decided to do.
Program P0 is the initial program for transaction TRX0.
We assume that all programs shown are issuing SQL calls.
Depending on the option chosen by the terminal user, program P0 performs a CICS transfer
control (XCTL) to one of the programs: P1, P2, or
P3.
After issuing some SQL calls, these programs display one of the maps: MAP1, MAP2, or MAP3.
The example shown on the right side of the figure works in the same way.
In some situations, program P3 transfers control to program PB.
