z/OS UNIX System Services (z/OS UNIX, or informally USS) is a base element of

z/OS z/OS is a 64-bit operating system for IBM z/Architecture mainframes, introduced by IBM in October 2000. It derives from and is the successor to OS/390, which in turn was preceded by a string of MVS versions.Starting with the earliest: * O ...

. z/OS UNIX is a certified

UNIX Unix (; trademarked as UNIX) is a family of multitasking, multiuser computer operating systems that derive from the original AT&T Unix, whose development started in 1969 at the Bell Labs research center by Ken Thompson, Dennis Ritchie, and ot ...

operating system An operating system (OS) is system software that manages computer hardware, software resources, and provides common services for computer programs. Time-sharing operating systems schedule tasks for efficient use of the system and may also in ...

implementation (

XPG4 X/Open group (also known as the Open Group for Unix Systems and incorporated in 1987 as X/Open Company, Ltd.) was a consortium founded by several European UNIX systems manufacturers in 1984 to identify and promote open standards in the field of in ...

UNIX 95) optimized for mainframe architecture. It is the first

UNIX 95 Unix (; trademarked as UNIX) is a family of multitasking, multiuser computer operating systems that derive from the original AT&T Unix, whose development started in 1969 at the Bell Labs research center by Ken Thompson, Dennis Ritchie, and ot ...

to not be derived from the

AT&T AT&T Inc. is an American multinational telecommunications holding company headquartered at Whitacre Tower in Downtown Dallas, Texas. It is the world's largest telecommunications company by revenue and the third largest provider of mobile tel ...

source code. Through integration with the rest of z/OS, additional

Time Sharing Option Time Sharing Option (TSO) is an interactive time-sharing environment for IBM mainframe operating systems, including OS/360 MVT, OS/VS2 (SVS), MVS, OS/390, and z/OS. Use In computing, time-sharing is a design technique that allows many people to ...

(TSO) commands are available alongside the usual UNIX services, making it possible to process UNIX files using

ISPF In computing, Interactive System Productivity Facility (ISPF) is a software product for many historic IBM mainframe operating systems and currently the z/OS and z/VM operating systems that run on IBM mainframes. It includes a screen editor, the us ...

. Extensions in JCL make it possible to use these files in

batch processing Computerized batch processing is a method of running software programs called jobs in batches automatically. While users are required to submit the jobs, no other interaction by the user is required to process the batch. Batches may automatically ...

Overview

UNIX System Services allows UNIX applications from other platforms to run on

IBM System z IBM Z is a family name used by IBM for all of its z/Architecture mainframe computers. In July 2017, with another generation of products, the official family was changed to IBM Z from IBM z Systems; the IBM Z family now includes the newest mode ...

mainframes running z/OS. In many cases only a recompile is necessary, although additional effort may be advisable for z/OS integration (such as

SMP/E System Modification Program/Extended (SMP/E), the proprietary version of System Modification Program (SMP), "is a tool designed to manage the installation of software products on z/OS system and to track the modifications" to those products. S ...

installation support). While z/OS UNIX supports ASCII and

Unicode Unicode, formally The Unicode Standard,The formal version reference is is an information technology Technical standard, standard for the consistent character encoding, encoding, representation, and handling of Character (computing), text expre ...

, and there's no technical requirement to modify ASCII and Unicode UNIX applications, many z/OS users often prefer

EBCDIC Extended Binary Coded Decimal Interchange Code (EBCDIC; ) is an eight-bit character encoding used mainly on IBM mainframe and IBM midrange computer operating systems. It descended from the code used with punched cards and the corresponding six- ...

support in their applications including those running in z/OS UNIX. Consequently, z/OS UNIX provides application and administrator services for converting to/from EBCDIC. Programs running under z/OS UNIX have full, secure access to the other internal functions of z/OS. Database access ( Db2 via Call Attach) is one example of how z/OS UNIX can access services found elsewhere in z/OS. Naturally such programs cannot be ported to non-mainframe platforms without rewriting if they use these z/OS-specific services. Conversely, if a program adheres to UNIX standards such as POSIX and

ANSI C ANSI C, ISO C, and Standard C are successive standards for the C programming language published by the American National Standards Institute (ANSI) and ISO/IEC JTC 1/SC 22/WG 14 of the International Organization for Standardization (ISO) and the ...

, it will be easier to move it between different UNIX operating systems including z/OS UNIX. The file systems for z/OS UNIX (the older HFS and the now preferred

zFS ZFS (previously: Zettabyte File System) is a file system with volume management capabilities. It began as part of the Sun Microsystems Solaris operating system in 2001. Large parts of Solaris – including ZFS – were published under an ope ...

), which support UNIX-style

long filename Long filename (LFN) support is Microsoft's backward-compatible extension of the 8.3 filename (short filename) naming scheme used in DOS. Long filenames can be more descriptive, including longer filename extensions such as .jpeg, .tiff, .html, a ...

s, appear as special

VSAM Virtual Storage Access Method (VSAM) is an IBM DASD file storage access method, first used in the OS/VS1, OS/VS2 Release 1 (SVS) and Release 2 (MVS) operating systems, later used throughout the Multiple Virtual Storage (MVS) architecture and now i ...

dataset A data set (or dataset) is a collection of data. In the case of tabular data, a data set corresponds to one or more database tables, where every column of a table represents a particular variable, and each row corresponds to a given record of the ...

s to the rest of z/OS. Numerous core z/OS subsystems and applications rely on UNIX System Services, including the z/OS Management Facility, XML parsing and generation services,

OpenSSH OpenSSH (also known as OpenBSD Secure Shell) is a suite of secure networking utilities based on the Secure Shell (SSH) protocol, which provides a secure channel over an unsecured network in a client–server architecture. Network Working Gr ...

, the IBM HTTP Server for z/OS, the z/OS SDK for

Java Java (; id, Jawa, ; jv, ꦗꦮ; su, ) is one of the Greater Sunda Islands in Indonesia. It is bordered by the Indian Ocean to the south and the Java Sea to the north. With a population of 151.6 million people, Java is the world's List ...

, and some z/OS PKI services as examples. z/OS UNIX also provides a

shell Shell may refer to: Architecture and design * Shell (structure), a thin structure ** Concrete shell, a thin shell of concrete, usually with no interior columns or exterior buttresses ** Thin-shell structure Science Biology * Seashell, a hard ou ...

environment, OMVS. z/OS UNIX's predecessor was an operating system component called

OpenEdition MVS z/OS UNIX System Services (z/OS UNIX, or informally USS) is a base element of z/OS. z/OS UNIX is a certified UNIX operating system implementation (XPG4 UNIX 95) optimized for mainframe architecture. It is the first UNIX 95 to not be derived fro ...

, first implemented in

MVS/ESA Multiple Virtual Storage, more commonly called MVS, was the most commonly used operating system on the System/370 and System/390 IBM mainframe computers. IBM developed MVS, along with OS/VS1 and SVS, as a successor to OS/360. It is unrelated ...

4.3 and enhanced in

5.1. OpenEdition MVS only supported the

POSIX The Portable Operating System Interface (POSIX) is a family of standards specified by the IEEE Computer Society for maintaining compatibility between operating systems. POSIX defines both the system- and user-level application programming interf ...

standards. IBM continues to enhance UNIX System Services. Typically every release of z/OS includes enhancements to z/OS UNIX.

References

External links

UNIX System Services
{{Unix IBM mainframe operating systems Unix variants

Overview

See also

References

External links