Is it possible to upgrade the mainframe Datacom Server to the latest release and keep the PC or client users on the previous release until ready to push out the PC or client upgrade?
The compatibility between different versions of the PC client ODBC and JDBC drivers and the mainframe versions is documented in section Version Compatibility Matrixes.
This matrix includes the compatibility of Datacom Server 15.0. It also includes the compatibility of earlier releases which are currently at end of support (EOS).
More information can be found in the mainframe README for CA Datacom Server 15.0
Also, review the readme.html file that is installed with the PC client software (Windows only).