The SYS% facility should only be used to allocate existing data sets. The SYS% facility can be used to build systems in an environment where the new and old data sets with the same names need to be cataloged in different catalogs at allocation time. For this reason, several functions are not supported in SYS% processing. Attempting them can cause undesired results or errors.

Do not attempt to use the SYS% facility to process SYS1 data sets with the DEFINE or ALTER commands. However, there is no restriction on using DEFINE or ALTER on data sets whose real data set name has a high level qualifier that can later be used by SYS%. For example, you can define a data set named SYSB.LINKLIB, and if SYSB is an alias to another system's master catalog, it is defined in that master catalog under the name SYSB.LINKLIB. Renaming the data set can then be accomplished if you have appropriate RACF® authority to the directed catalog FACILITY class profile.

Errors result if you expect DEFINE, ALTER, or LISTCAT LEVEL to convert a SYS% alias to SYS1.

You can use the SYS% facility to delete data sets only if you use their fully-qualified data set names (a "discrete" deletion). You can do this during disposition processing or through access method services. For example, if the real data set name is "SYS1.LINKLIB", you can allocate and delete the data set using "SYSB.LINKLIB" if the alias "SYSB" is properly defined. Do not attempt to generically delete a group of SYS1 data sets using a SYS% alias by specifying "SYSB.*".

Do not use indirect volume serial numbers (for example, ******) when using SYS% conversion. Use specific volume serial numbers for all references to SYS1 data sets. Indirect volume serial numbers resolve to the IPL volume of the system running the job.

Be careful if you attempt to use SYS% conversion with the ISPF/PDF utilities, ISMF, and TSO commands. Unexpected results can occur, since these programs sometimes use generic functions.