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VSE-ON-MVS is a set of assembler macro instructions and run-time routines which allows VSE programs to be assembled and run on any MVS/ESA, OS/390 or z/OS system. VSE-ON-MVS was initially designed and developed to allow 5000 existing assembler programs running in 35 VSE data centers to assemble and run, unchanged, as these data centers were gradually migrated to MVS/ESA and OS/390. VSE-ON-MVS is also used at GSF Software to develop and test VSE programs in the z/OS environment.
VSE-ON-MVS is a source-level simulator. In order to run successfully in the VSE-ON-MVS environment, VSE assembler programs must be assembled using the VSE-ON-MVS macro-instruction library. Note that VSE-ON-MVS is different from binary emulators like CA-DUO (aka CA2 or UCC2/DUO) which allow the execution of VSE object code (PHASEs) in the MVS environment.
VSE-ON-MVS supports main programs and sub-programs. Sub-programs can be invoked from any language supported by MVS. Note that VSE-ON-MVS does not offer any facility for languages other than assembler.
VSE-ON-MVS supports most of the VSE system macro-instructions and services used in application programs, including the following:
The following are not supported:
SHOWDTF & MODDTF are two VSE-ON-MVS macro-instructions that programs can use to extract information from a DTF or modify it. Both macros assemble in the native VSE environment to generate VSE code, and in the VSE-ON-MVS environment to generate equivalent MVS code. SHOWDTF can be used, for example to extract the block count or volume serial number for a tape file. MODDTF can, among other things, change the RECFORM, RECSIZE and BLKSIZE values in a DTFSD.
VSE-ON-MVS consists of a library of macro-instructions and an authorised load library. The load library contains a set of run-time modules, a type-3 SVC routine, and a tool to install and remove the SVC routine without requiring a system IPL.
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