UNIX System Services (USS) is a required component of z/OS. USS is a certified UNIX implementation (XPG4 UNIX 95) optimized for mainframe architecture. It is the first UNIX 95 which was not derived from the AT&T source code. Through integration with the rest of z/OS, additional time share option (TSO) commands are available alongside the usual UNIX services, making it possible to process UNIX files using ISPF. Extensions in JCL make it possible to use these files in batch processing. Software component representations: above the representation used in UML, below the representation commonly used by Microsofts COM objects. ... z/OS Welcome Screen seen through a terminal emulator The title of this article begins with a capital letter due to technical limitations. ... Filiation of Unix and Unix-like systems Unix (officially trademarked as UNIX®) is a computer operating system originally developed in the 1960s and 1970s by a group of AT&T employees at Bell Labs including Ken Thompson, Dennis Ritchie and Douglas McIlroy. ... X/Open Portability Guide Issue 4 Also known as Common Applications Environment Specification Issue 4. ... The Single UNIX Specification (SUS) is the collective name of a family of standards for computer operating systems to qualify for the name Unix. The SUS is developed and maintained by the Austin Group, based on earlier work by the IEEE and The Open Group. ... AT&T (NYSE: T) is the largest provider of both local and long distance telephone services, wireless service (formerly known as Cingular Wireless), and DSL Internet access in the United States. ... 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. ... ISPF (Interactive System Productivity Facility) is a tool set for the IBM z/OS (MVS, OS/390) operating system for mainframe computers. ... 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. ...

UNIX System Services allows UNIX applications from other platforms to run on IBM mainframes. In many cases only a recompile is necessary, although additional effort may be advisable for z/OS integration (such as SMP/E installation support). Binary programs using hardcoded ASCII numerical values may need adjustment — z/OS users often prefer or require EBCDIC support. Programs running under USS have full, secure access to the internal functions of z/OS. Database access (DB2 via Call Attach) is one example of how USS can access services found elsewhere in z/OS. Naturally such programs cannot be ported to non-mainframe platforms without rewriting should they use these z/OS-specific services. Conversely, if a program adheres to standards such as POSIX and ANSI C, it will be easier to port to the USS environment. SAS 8 on an IBM mainframe under 3270 emulation An IBM mainframe is a mainframe computer made by IBM. // From 1952 into the late 1960s, IBM manufactured and marketed several large computer models, known as the IBM 700/7000 series. ... ... There are 95 printable ASCII characters, numbered 32 to 126. ... 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... DB2 is IBMs line of RDBMS (or, as IBM now calls it, data server) software products within IBMs broader Information Management software line. ... ANSI C (Standard C) is a variant of the C programming language. ...

The file systems for USS (the older HFS and the now preferred zFS), which support UNIX-style long filenames, appear as special datasets to the rest of z/OS. Numerous core System z subsystems and applications rely on UNIX System Services, including Java. The term data set or dataset is used to refer to files on an IBM mainframe computer, typically stored on DASD or magnetic tape. ... Java is an object-oriented programming language developed by Sun Microsystems in the early 1990s. ...

USS also provides a shell environment, OMVS.

USS's predecessor was an operating system component called OpenEdition MVS, first implemented in MVS/ESA 4.3. OpenEdition MVS only supported the POSIX standards. MVS (Multiple Virtual Storage) was the most commonly used operating system on the System/370 and System/390 IBM mainframe computers. ... MVS/ESA: MVS Enterprise System Architecture. ... POSIX or Portable Operating System Interface for uniX is the collective name of a family of related standards specified by the IEEE to define the application programming interface (API) for software compatible with variants of the Unix operating system. ...

See also

• Linux on zSeries

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. ...

External links

• UNIX System Services