If you want to share the CSD between CICS® regions at different release levels, to enable you to share common resource definitions, you must update the CSD from the higher level region - CICS Transaction Server for z/OS®, Version 3 Release 1.
In CICS Transaction Server for z/OS, Version 3 Release 1, some attributes are obsolete, and are removed from the CSD definitions. Using the ALTER command on definitions that specify obsolete attributes does not cause the loss of these attributes in CICS Transaction Server for z/OS, Version 3 Release 1, so you can safely update resource definitions from a CICS Transaction Server for z/OS, Version 3 Release 1 region. If you are sharing the CSD between a CICS Transaction Server for z/OS, Version 3 Release 1 region and a CICS/MVS 2.1.2 or a CICS/OS/VS 1.7 region, you can use the CICS Transaction Server for z/OS, Version 3 Release 1 CSD utility, DFHCSDUP, to update resources that specify obsolete attributes. A compatibility option is added for this purpose, which you must specify on the PARM parameter on the EXEC PGM=DFHCSDUP statement. You indicate the compatibility option by specifying COMPAT or NOCOMPAT. The default is NOCOMPAT, which means that you cannot update obsolete attributes. (See Figure 37.) the CICS Transaction Server for z/OS Migration from CICS TS Version 2.3 discusses these obsolete attributes and their compatibility with earlier releases.