5 Key features of CICS function Shipping

Function shipping is a concept in CICS to access resource from outside of current CICS region. The below figure and important key points explained very well to understand quickly.

When function shipping is used

The following example explains very well…

There are two areas one is CICA and the other one is CICB.

In the following figure, a transaction running in CICA issues a file control READ command against a file called NAMES.

“The resource definition for the file indicates that this file is owned by a remote CICS system called CICB.”

CICS changes the READ request into a suitable transmission format and then ships it to CICB for execution.

Function shipping is applicable when you access a file or object from remote CICS system.

The picture shows two CICS systems, CICA and CICB, which are connected by an IPIC, ISC, or MRO link. On CICA, the definition of a file called “NAMES” specifies REMOTESYSTEM(CICB). On CICB, “NAMES” is defined as a local file. A program on CICA issues an EXEC CICS READ FILE(NAMES) command. CICA sees that “NAMES” is owned by CICB and ships the request to CICB. In CICB, the mirror transaction is attached. The mirror issues the READ command against “NAMES” and passes the retrieved data back to the program on CICA.

The below are the 5 key features, which everyone should know about Function Shipping in CICS.

  • Access CICS files owned by other CICS systems by shipping file control requests.
  • Access DL/I databases managed by or accessible to other CICS systems by shipping requests for DL/I functions.
  • Transfer data to or from transient data and temporary storage queues in other CICS systems by shipping requests for transient data and temporary storage functions.
  • Initiate transactions in other CICS systems, or other non-CICS systems that implement SNA LU Type 6 protocols, such as IMS™, by shipping interval control START requests. This form of communication is described in Asynchronous processing.
  • You can write applications without regard to the location of the requested resources. They use file control commands, temporary-storage commands, and other functions in the same way.
  • Entries in the CICS resource definition tables allow the system programmer to specify that the named resource is not on the local (or requesting) system but on a remote (or owning) system.

Read more about CICS function shipping examples.

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Author: Srini

Experienced software developer. Skills in Development, Coding, Testing and Debugging. Good Data analytic skills (Data Warehousing and BI). Also skills in Mainframe.