Overview#Multiple Virtual Storage (MVS), was the most commonly used Operating System on the System/370 and System/390 IBM mainframe computers.
First released in 1974, Multiple Virtual Storage was extended by program products with new names multiple times:
- first to MVS/SE (MVS/System Extensions),NB 1
- next to MVS/SP (MVS/System Product) Version 1,
- next to MVS/XA (MVS/eXtended Architecture),
- next to MVS/ESA (MVS/Enterprise Systems Architecture),
- then to OS/390 and
- finally to z/OS (when 64-bit support was added with the zSeries models).
IBM added UNIX support (originally called OpenEdition MVS) in MVS/SP V4.3 and has obtained POSIX and UNIX™ certifications at several different levels from IEEE, X/Open and The Open Group. The MVS core remains fundamentally the same Operating System.