Introduction to DPL

When a CICS® application program issues an EXEC CICS LINK command, control passes to a second program, named in the command. The second program executes and, when it completes, control returns to the first program at the instruction following the LINK command. The linked-to program can return data to the linking program in either of the following cases:

Distributed program link (DPL) extends the use of the EXEC CICS LINK command so that the linking and linked-to programs can be in different CICS systems. The systems can be copies of the same CICS product or of different CICS products.

In certain circumstances, the use of DPL can improve performance by reducing the number of data flows between connected CICS systems.

You can specify that the linked program is to run on a connected CICS system by coding the SYSID option in the LINK command, or by specifying the remote system name in the local definition of the program.

In Figure 8, program A links to a program B, which is in a different CICS system. The arrowed line represents the flow of control. To program A, program B appears as a called subroutine.

Figure 8. Distributed program link
 The picture shows two connected CICS regions. Program A, running on the left region, issues an EXEC CICS LINK PROGRAM request for program B, which is owned by the right region. The LINK request is shipped to the right region, where program B is attached. When program B issues an EXEC CICS RETURN command, control is returned to program A on the left region.

Related concepts
Why use DPL?
Synchronization
DL/I and SQL databases
Restrictions when using DPL
Abends when using DPL
Related reference
CICS product communication support
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