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MVS (Multiple Virtual Storage) was the most commonly used operating system on the System/370 and System/390 IBM mainframe computers. It is unrelated to IBM's other mainframe operating system called VM/CMS. To meet Wikipedias quality standards, this article or section may require cleanup. ... IBM logo The IBM System/370 (often: S/370) was a model range of IBM mainframes announced on June 30, 1970 as the successors to the System/360 family. ... The title given to this article is incorrect due to technical limitations. ... An IBM mainframe is an International Business Machines (IBM)-made mainframe computer, i. ... International Business Machines Corporation (IBM, or colloquially, Big Blue) (NYSE: IBM) (incorporated June 15, 1911, in operation since 1888) is headquartered in Armonk, New York, USA. The company manufactures and sells computer hardware, software, and services. ... VM/CMS (Virtual Machine/Conversational Monitor System, originally called CP/CMS when it first appeared) is a bundled pair of operating systems used on IBM System/360, System/370, System/390, zSeries, and System z9 mainframes (and compatible systems). ...


First released in 1974, MVS was later renamed by IBM, first to MVS/XA (eXtended Architecture), next to MVS/ESA (Enterprise Systems Architecture), then to OS/390 when UNIX System Services (USS) were added, and finally to z/OS when 64-bit support was added on the zSeries models. Its core remains fundamentally the same operating system. By design, programs written for MVS can still run on z/OS without modification. MVS/XA stands for This was a version of z/OS, which supported 31-bit addressing. ... MVS/ESA: MVS Enterprise System Architecture. ... OS/390 is an IBM operating system for the System/370 and System/390 IBM mainframe computers. ... Unix System Services (USS) is a component of z/OS. USS is an adequate, certified Unix implementation (XPG4 UNIX 95). ... z/OS Welcome Screen seen through a terminal emulator The title of this article begins with a capital letter due to technical limitations. ... In computing, a 64-bit component is one in which data are processed or stored in 64-bit units (words). ... Since December, 2001, IBM designates all its mainframes with the name eServer zSeries, with the e depicted in IBMs well-known red trademarked symbol. ...


MVS descends from SVS (Single Virtual Storage), which in turn descends from MVT, one of the original variants of OS/360. The first variant of OS/360, PCP (Primary Control Program), did not support multitasking. MVT (Multitasking with a Variable number of Tasks) was an enhancement that provided that functionality. SVS added virtual storage (more commonly known outside IBM as virtual memory), with the same address space being shared by all tasks. Finally, MVS allowed different tasks to have different address spaces. MVT is an acronym for Multiprogramming with a Variable number of Tasks. ... OS/360 was a batch processing operating system developed by IBM for their then-new System/360 mainframe computer, announced in 1964. ... In computing, multitasking is a method by which multiple tasks, also known as processes, share common processing resources such as a CPU. In the case of a computer with a single CPU, only one task is said to be running at any point in time, meaning that the CPU is... The memory pages of the virtual address space seen by the process, may reside non-contiguously in primary, or even secondary storage. ...


MVS originally supported 24-bit addressing. As the underlying hardware progressed it supported 31-bit (XA and ESA) and now (as z/OS) 64-bit addressing.


The main interfaces to MVS are JCL (Job Control Language), the batch processing interface, and TSO (Time Sharing Option), the interactive time-sharing interface, which originally was optional but is now a standard component. ISPF is an interface which allows the user to accomplish the same tasks as TSO but in a menu and form oriented manner. Job Control Language (JCL) is a scripting language used on IBM mainframe operating systems to instruct the Job Entry Subsystem (that is, JES2 or JES3) on how to run a batch program or start a subsystem. ... Batch processing is the sequential execution of a series of programs (jobs) on a computer. ... Time Sharing Option (TSO) is an interactive command line interpreter for IBM mainframe operating systems such as MVS/ESA, OS/390 and z/OS. It fills the same purpose as a command shell like Bash on Unix, or cmd on Windows. ... There are several conceptual views of interactivity, the most general being the contingency view. ... Alternate uses: see Timesharing Time-sharing is an approach to interactive computing in which a single computer is used to provide apparently simultaneous interactive general-purpose computing to multiple users by sharing processor time. ... ISPF (Interactive System Productivity Facility) is a tool set for the IBM z/OS (MVS, OS/390) operating system for mainframe computers. ...


The system is typically used in business and banking, and applications are often written in COBOL. COBOL programs were traditionally used with transaction processing systems like IMS and CICS. For a program running in CICS, special EXEC CICS statements are inserted in the COBOL source code. A preprocessor (translator) replaces those EXEC CICS statements with the appropriate COBOL code to call CICS before the program is compiled — not altogether unlike SQL used to call DB2. Applications can also be written in other languages such as C, C++, Java, assembly language, Fortran, BASIC, RPG, and REXX. Language support is packaged as a common component called "Language Environment" or "LE" to allow uniform debugging, tracing, profiling, and other language independent functions. COBOL is a third-generation programming language, and one of the oldest programming languages still in active use. ... Information Management System (IMS) is a joint hierarchical database and information management system. ... CICS® (Customer Information Control System) is a transaction server that runs primarily on IBM mainframe systems under z/OS or z/VSE. CICS is available for other operating systems, notably i5/OS, OS/2, and as the closely related IBM TXSeries software on AIX, Windows, and Linux, among others. ... SQL (commonly expanded to Structured Query Language — see History for the terms derivation) is the most popular computer language used to create, modify, retrieve and manipulate data from relational database management systems. ... DB2 is IBMs line of RDBMS (or, as IBM now calls it, data server) software products within IBMs broader Information Management software line. ... Wikibooks has a book on the topic of C Programming The C programming language (often, just C) is a general-purpose, procedural, imperative computer programming language developed in the early 1970s by Dennis Ritchie for use on the Unix operating system. ... C++ (generally pronounced /si plÊŒs plÊŒs/) is a general-purpose, high-level programming language with low-level facilities. ... Java is an object-oriented programming language developed by James Gosling and colleagues at Sun Microsystems in the early 1990s. ... To meet Wikipedias quality standards, this article or section may require cleanup. ... Fortran (previously FORTRAN[1]) is a general-purpose[2], procedural,[3] imperative programming language that is especially suited to numeric computation and scientific computing. ... BASIC (Beginners All-purpose Symbolic Instruction Code) is a family of high-level programming languages. ... RPG is a native programming language for IBMs iSeries servers - the latest generation of midrange servers which included System/38, System/36, AS/400, iSeries and System i5 systems. ... REXX (REstructured eXtended eXecutor) is an interpreted programming language which was developed at IBM. It is a structured high-level programming language which was designed to be both easy to learn and easy to read. ...


MVS systems are traditionally accessed by 3270 terminals or by PCs running 3270 emulators. However, many mainframe applications these days have custom web or GUI interfaces. The z/OS operating system has built-in support for TCP/IP. System management, done in the past with a 3270 terminal, is now done through the Hardware Management Console (HMC) and, increasingly, Web interfaces. Operator consoles are provided through 2074 emulators, so you are unlikely to see any S/390 or zSeries processor with a real 3270 connected to it. The z/OS operating system also has native support to execute POSIX applications. Clemson Universitys library catalog displayed in a 3270 emulation program The IBM 3270 is a class of terminals made by IBM since 1972 (known as Display Devices) normally used to communicate with IBM mainframes. ... WWWs historical logo designed by Robert Cailliau The World Wide Web (WWW or simply the Web) is a global, read-write information space. ... This article or section needs a complete rewrite for the reasons listed on the talk page. ... The Internet protocol suite is the set of communications protocols that implement the protocol stack on which the Internet and most commercial networks run. ... To meet Wikipedias quality standards, this article or section may require cleanup. ...


Files are called "data sets" in MVS. These files are organized in "catalogs." The native encoding scheme of MVS is Big Endian EBCDIC, but MVS provides hardware-accelerated services to perform translation and support of ASCII, Little Endian, and Unicode. When integers or any other data are represented with multiple bytes, there is no unique way of ordering of those bytes in memory or in a transmission over some medium, and so the order is subject to arbitrary convention. ... EBCDIC (Extended Binary Coded Decimal Interchange Code) is an 8-bit character encoding (code page) used on IBM mainframe operating systems, like z/OS, OS/390, VM and VSE, as well as IBM minicomputer operating systems like OS/400 and i5/OS. It is also employed on various non-IBM... There are 95 printable ASCII characters, numbered 32 to 126. ... When integers or any other data are represented with multiple bytes, there is no unique way of ordering of those bytes in memory or in a transmission over some medium, and so the order is subject to arbitrary convention. ... Because of technical limitations, some web browsers may not display some special characters in this article. ...


One instance of MVS can occupy an entire physical system, a "Logical Partition" (or "LPAR"), or a virtual machine under z/VM. Multiple MVS instances can be organized and collectively administered in a structure called a "Systems Complex" or "Sysplex," introduced in September, 1990. LPARs interoperate through a software component called a "Cross-system Coupling Facility" or "XCF" and a hardware component called a "Hardware Coupling Facility" or "CF" (or "ICF" if co-located on the same mainframe hardware). Multiple Sysplexes can be joined via standard network protocols such as TCP/IP or IBM's proprietary Systems Network Architecture (SNA). LPARs can also run other operating systems, such as Linux on zSeries, z/VSE, z/TPF, or z/VM. In IBM mainframe computing, a Logical Partition, commonly called an LPAR, is a virtualized computing environment abstracted from all physical devices. ... VM is an early and influential virtual machine operating system from IBM, apparently the first true virtual machine system. ... In IBM mainframe computers, a Systems Complex, commonly called a Sysplex, is one or more System/390 processors joined into a single unit, sharing the same Sysplex name and CDS. Put another way, a Sysplex is an instance of a computer system running on one or more physical computers. ... This article is about the year. ... Systems Network Architecture (SNA) is IBMs proprietary networking architecture created in 1974. ... Linux on zSeries (or Linux on System z9) is the preferred collective term for the Linux operating system and GNU/Linux software compiled to run on IBM mainframes, especially zSeries servers. ... VSE (Virtual Storage Extended) is an operating system on the IBM System/370 and System/390 mainframe computers. ... TPF is also the NASA Terrestrial Planet Finder project. ... VM is an early and influential virtual machine operating system from IBM, apparently the first true virtual machine system. ...

Contents

MVS filesystem

MVS's classic filesystem is a record-oriented filesystem. Filenames are organized in a hierarchy, separated with dots. Each level in the hierarchy can be up to eight characters long. The total filename length is a maximum of 44 characters. This article needs to be wikified. ...


Generally, the components separated by the dots are used to organize files similarly to directories in other operating systems. For example, the higher level components generally represent project and user names. However, unlike other systems, these are not actual directories, just a naming convention. TSO supports a default prefix for files (similar to a "current directory" concept), and RACF supports setting up access controls based on filename patterns, analogous to access controls on directories on other platforms. Time Sharing Option (TSO) is an interactive command line interpreter for IBM mainframe operating systems such as MVS/ESA, OS/390 and z/OS. It fills the same purpose as a command shell like Bash on Unix, or cmd on Windows. ... RACF, short for Resource Access Control Facility, is an IBM software product. ...


Partitioned datasets are in some ways similar to single level directories. MVS supports a wide array of file access methods, mainly due to legacy needs. These include VSAM, BSAM, QSAM, and others. The MVS filesystem is based on the VTOC disk structure that IBM has used for many years. Virtual Sequential Access Method (VSAM) is an IBM disk file storage scheme first used in the S/370 and virtual storage. ... In the z/OS architecture from IBM, this refers to the Volume Table Of Contents. ...


Modern versions of MVS (i.e. z/OS) also support POSIX-compatible "slash" filesystems along with facilities for integrating the two filesystems. That is, the OS can make an MVS dataset appear as a file to a POSIX program, and an MVS dataset can be made to appear as a file to the POSIX subsystem. These newer filesystems include Hierarchical File System (HFS) and zFS (not to be confused with Sun's ZFS). ZFS is a three-letter abbreviation with multiple meanings, as described below: the file system ZFS in Solaris 10 from Sun Microsystems Zope File System - for Zope Zipper-based file server - for FreeBSD and Linux, written in the Haskell programming language zFS - A Scalable Distributed File System using Object Stores...


History and modernity

MVS is no longer supported by IBM. In fact, IBM is phasing out support for the 31-bit compatible versions of z/OS by 2007, so only the 64-bit z/OS versions will enjoy support after that date. z/OS continues to receive cutting edge improvements to extend its leadership as the flagship enterprise operating system. In addition to those enhancements mentioned above, others include:

  • XML (Xerces-based toolkits for C/C++ and Java)
  • network file systems
  • TLS/SSL support throughout (including the TCP/IP stack level)
  • removal of previous architectural limits (such as the number of I/O channels)
  • encrypting file systems
  • Workload Manager (WLM)
  • special Java acceleration (zAAP support)
  • Hipersockets

While z/OS continues to run older 24-bit MVS applications, it does so alongside just written 64-bit hardware-accelerated Java running with state-of-the-art security and Unicode XML data formats on protected filesystems with flexible mounting and long filenames, communicating across IPv6 Hipersocket virtual networks and/or high speed CFs to 64-bit geographically clustered relational databases that use the latest performance-enhancing SQL features including materialized query tables and cube views — for example. Xerces is a family of software packages for parsing and manipulating XML, part of the Apache XML project. ... Network File System (NFS) is a protocol originally developed by Sun Microsystems in 1984 and defined in RFCs 1094, 1813, and 3530 (obsoletes 3010), as a distributed file system which allows a computer to access files over a network as easily as if they were on its local disks. ... To meet Wikipedias quality standards, this article or section may require cleanup. ... Secure Sockets Layer (SSL) and its successor, Transport Layer Security (TLS), are cryptographic protocols which provide secure communications on the Internet for such things as web browsing, e-mail, Internet faxing, and other data transfers. ... zAAP is the zSeries Application Assist Processor, a mainframe processor introduced by IBM in 2004. ... Hipersocket is an IBM technology for high-speed communications between partitions on a server with a hypervisor. ... Internet Protocol version 6 (IPv6) is a network layer IP standard used by electronic devices to exchange data across a packet-switched internetwork. ...


See also

  • Hercules a S/370, S/390, and zSeries emulator capable of running MVS

The Hercules emulator is an emulator for the IBM mainframe hardware: the System/370, System/390 and zSeries computers. ...

References

  • Bob DuCharme: "The Operating Systems Handbook, Part 06: MVS" (available online here)

External links

  • IBM: z/OS V1R8.0 MVS manuals
  • MVS: the operating system that keeps the world going
  • MVS... a long history

  Results from FactBites:
 
What is MVS? - a definition from Whatis.com - see also: Multiple Virtual Storage (824 words)
MVS has been said to be the operating system that keeps the world going and the same could be said of its successor systems, OS/390 and z/OS.
Although MVS has often been seen as a monolithic, centrally-controlled information system, IBM has in recent years repositioned it (and successor systems) as a "large server" in a network-oriented distributed environment, using a 3-tier application model.
MVS is considerably more complex and requires much more education and experience to operate than smaller server and personal computer operating systems.
MVS - Wikipedia, the free encyclopedia (957 words)
MVS (Multiple Virtual Storage) was the most commonly used operating system on the System/370 and System/390 IBM mainframe computers.
MVS descends from SVS (Single Virtual Storage), which in turn descends from MVT, one of the original variants of OS/360.
The MVS filesystem is based on the VTOC disk structure that IBM has used for many years.
  More results at FactBites »

 
 

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