Non-System/390® CICS application programs can access resources (data or transactions) owned by a CICS® on System/390 system, and a CICS on System/390 application can access resources owned by a non-System/390 CICS system, in each case provided that the resources are defined as remote in the function shipping system.
A function shipping request takes the form of a normal EXEC CICS command. If either of the following conditions applies, the application-owning system recognizes that function shipping is required and ships the request to the remote resource-owning system.
The mirror program in each CICS product (DFHMIRS in CICS on System/390) handles inbound function shipping.
As already noted, the LU 6.2 protocol is used for all communication between System/390 and non-System/390 CICS systems. Synchronization level 2 on LU 6.2 links is supported by CICS on Open Systems and CICS/400. It is not supported by CICS Transaction Server for Windows. Synchronization level 1 is supported for function shipping between all non-System/390 and System/390 CICS systems. See Syncpointing (LU 6.2).
There are some restrictions on function shipping between System/390 and non-System/390 CICS systems.
Function shipping the following sequence of commands from a non-System/390 CICS to a CICS on System/390 system causes the System/390 mirror transaction to abend:
DELETEQ TS Q(RFRED)
WRITEQ TS Q(RFRED) FROM()
SYNCPOINT
This is because, on CICS on System/390, you cannot delete a recoverable temporary storage queue and then write to it, without issuing a syncpoint between the two commands.
Non-System/390 CICS systems cannot function-ship requests to DL/I databases accessed through CICS on System/390 systems. To access DL/I databases from CICS Transaction Server for Windows, CICS on Open Systems, or CICS/400, use distributed transaction processing or the distributed program link function.
CICS Transaction Server for Windows and CICS on Open Systems use ASCII1 data representation and CICS/400 and CICS on System/390 systems use EBCDIC2. When conversion is necessary, the ASCII-based system always converts system data such as resource names. Conversion of user data is performed as necessary in the resource-owning system. For example, for CICS TS for Windows->CICS function shipping, CICS converts the user data (see Table 2). For CICS->CICS TS for Windows function shipping, CICS TS for Windows converts the user data.