by Robert Sample » Tue Mar 16, 2010 11:30 pm
From an application standpoint, I can't think of the last time a CICS release was not compatible with earlier releases -- except when IBM dropped support for macro code, and this was announced for years before it happened. There generally is new functionality that requires application code changes to take advantage of, but the application will almost always continue to run under the new release without change.
If you look in the CICS 4.1 Language Reference and Programming Guide manuals, they will list any application issues near the front of the manual.