The CL compiler retrieves information about previous-release commands and files from CL previous-release (*PRV) libraries.
Two types of libraries contain previous-release support: system libraries and user libraries. The libraries have the names QSYSVxRxMx and QUSRVxRxMx. (VxRxMx represents the version, release, and modification level of the supported previous release). For example, the QUSRV4R5M0 library supports a system that runs Version 4 Release 5 Modification level 0 of the i5/OS™ licensed program.
When the CL compiler compiles for a supported previous release, it first checks for commands and files in the previous-release libraries. When failing to find the command or file in the previous-release libraries, the system performs a search of the library list (*LIBL) or the qualified library.
QSYSVxRxMx Libraries: The QSYSVxRxMx libraries install at the same time as the CL compiler support for a previous release installs. The QSYSVxRxMx libraries include the command definition objects and output files (*OUTFILE) that are found in library QSYS for that particular previous release.
QUSRVxRxMx Libraries: You can create your own QUSRVxRxMx libraries to hold copies of your commands and files as they existed in the supported previous release. This is especially important if the commands or files have changed on the current release.
When the compiler looks for previous-release commands and files, it checks the QUSRVxRxMx library (if it exists) before checking the QSYSVxRxMx library.
Do not add previous-release libraries to the library list (*LIBL). They contain commands and files that support earlier releases and cannot run on the current system. Only the CL compiler refers to and uses the commands and files in the previous-release libraries. The system commands that are supplied for a previous release are in the primary language for the system. There are no secondary national language versions available.