Joined: 29 Jul 2003
OS/390 is an integrated enterprise server operating system. It incorporates into one product a leading-edge and open communications server, distributed data and file services, Parallel Sysplex system support, object-oriented programming, distributed computer environment (DCE), and open application interface. As such, it is uniquely suited to integrate today?s heterogeneous and multi-vendor environments.
By incorporating the base operating system, it continues to build on the classic strengths of MVS: its reliability, continuous availability features, and security. This provides a scalable system that supports massive transaction volumes and large numbers of users with high performance, as well as advanced system and network management, security, and 24/7 availability.
OS/390 Release 1 was introduced as a replacement for MVS/ESA Version 5 Release 2. There have now been eight releases of OS/390,
Before OS/390, installations used an MVS operating system that consisted of:
1) The Base Control Program (BCP)
The BCP provides essential operating system services. The BCP includes the I/O configuration program (IOCP) as well as the function that starts the OS/390 UNIX System Services address space. This latter function was called OpenEdition System Services and was a nonexclusive base element of OS/390 R1, was an exclusive element of OS/390 R2, was integrated into the BCP element in OS/390 R3, and in OS/390 R6 remained as a part of the BCP but its name was changed to OS/390 UNIX System Services.
3) JES2 or JES3
4) TSO/E and ISPF
5) A collection of other software products that applications required
With OS/390, IBM integrated these products and offered a single product.
With OS/390, you may order new levels of some products but not of others; instead, you order and install an entire set of products integrated into one functionally rich operating system. Once positioned on OS/390, you can receive new functions and levels approximately every six months.
This predictable release cycle helps reduce planning time. Because each new level is comprehensively tested, the quality of the operating system is improved. Once your initial migration is complete, you can expect simplified ordering, planning, and installing, freeing you to increase the
value of your computing environment to your business and deliver better service to your end users.
Hope this explanation helps.