Using the CICS business logic interface to call a program

Figure 1 shows the control flow through the CICS® business logic interface to a program. The CICS business logic interface is accessed by a LINK command to PROGRAM DFHWBBLI.

Figure 1. Calling a program with the CICS business logic interface—control flow
Calling a program with the —control flow
  1. A request arrives for the CICS business logic interface.
  2. If the caller requests a converter, the CICS business logic interface calls it, requesting the Decode function. Decode sets up the COMMAREA for the CICS application program.
  3. The CICS business logic interface calls the CICS application program that the caller specified. The COMMAREA passed to the application program is the one set up by Decode. If the caller of the CICS business logic interface indicates that a converter is not required, the first 32K bytes of the request is passed to the CICS application program in its COMMAREA.
  4. The CICS application program processes the request, and returns output in the COMMAREA.
  5. If the caller requested a converter, the CICS business logic interface calls the Encode function of the converter, which uses the COMMAREA to prepare the response. If no converter program was called, the CICS business logic interface assumes that the CICS application program has put the desired response in the COMMAREA.
  6. The CICS business logic interface sends a reply back to the caller.