Changes to the application programming interface

Program compatibility

CICS provides API compatibility from release to release. However, functional changes to some CICS components can affect some CICS API commands.

Except for the specific cases described in these topics, CICS Transaction Server provides compatibility with future releases, at source and object level, for all CICS application programs that are written to the CICS application programming interface and which run correctly under the previous release.

For information about CICS support for application programming languages, see High level language support.

Application program mask setting following a handled condition

CICS TS for z/OS, Version 5.2 resolves the problem reported in APAR PM73097. Previously, when CICS handled a condition encountered by an application as requested by an earlier EXEC CICS HANDLE CONDITION command, the application's program mask was set to zero in the PSW. As a consequence, in the event of a subsequent program exception in a PL/I program, such as an overflow, no interrupt occurred. Now, when CICS handles a condition, the application's program mask is correctly restored to the value that it had when the EXEC CICS HANDLE CONDITION command was issued.

COMMAREA length on XCTL commands

When a communication area (COMMAREA) is used with an XCTL command, CICS now creates the COMMAREA in 31-bit storage, rather than 24-bit storage, where appropriate, to reduce the use of 24-bit storage.

When XCTL is used, CICS now ensures that any COMMAREA is addressable by the program that receives it, by creating the COMMAREA in an area that conforms to the addressing mode of the receiving program. If the receiver is AMODE(24), the COMMAREA is created below the 16 MB line, and if the receiver is AMODE(31), the COMMAREA is created above 16 MB but below 2 GB. In earlier releases of CICS, the COMMAREA was always copied below the 16 MB line.

Because the COMMAREA can now be in 31-bit storage, ensure that the XCTL commands in your applications specify an accurate length for the COMMAREA. If the value specified for the LENGTH option differs from the length of the data area specified in the COMMAREA option, a destructive overlap might occur when the data is being copied, because of the incorrect length. In this situation, CICS returns a LENGERR response with a RESP2 value of 28 to the application.

DFH3QSS program

If any of your applications call the DFH3QSS program to query the CICS environment and API capability, re-link those applications with the version of DFH3QSS supplied with CICS TS for z/OS, Version 5.2.