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: ...

. z/OS UNIX is a certified

UNIX Unix (, ; trademarked as UNIX) is a family of multitasking, multi-user 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, a ...

operating system An operating system (OS) is system software that manages computer hardware and software resources, and provides common daemon (computing), services for computer programs. Time-sharing operating systems scheduler (computing), schedule tasks for ...

implementation ( XPG4 UNIX 95) optimized for mainframe architecture. It is the first UNIX 95 to not be derived from the

AT&T AT&T Inc., an abbreviation for its predecessor's former name, the American Telephone and Telegraph Company, is an American multinational telecommunications holding company headquartered at Whitacre Tower in Downtown Dallas, Texas. It is the w ...

source code. Through integration with the rest of z/OS, additional Time Sharing Option (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 Text editor, screen e ...

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

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 will soon include the newest ...

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

Unicode Unicode or ''The Unicode Standard'' or TUS is a character encoding standard maintained by the Unicode Consortium designed to support the use of text in all of the world's writing systems that can be digitized. Version 16.0 defines 154,998 Char ...

, 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 si ...

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, 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 HFS may refer to: Businesses and organisations * Croatian Film Association () * Hellenic Fire Service, Greece * Hospitality Franchise Systems, US Computing * Hierarchical file system, a system for organizing directories and files * Hierarchica ...

with DFSMS/MVS Version 1 Release 2 and the now preferred

zFS ZFS (previously Zettabyte File System) is a file system with Volume manager, volume management capabilities. It began as part of the Sun Microsystems Solaris (operating system), Solaris operating system in 2001. Large parts of Solaris, includin ...

), which support UNIX-style long filenames, appear as datasets 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, the IBM HTTP Server for z/OS, the z/OS SDK for

Java Java is one of the Greater Sunda Islands in Indonesia. It is bordered by the Indian Ocean to the south and the Java Sea (a part of Pacific Ocean) to the north. With a population of 156.9 million people (including Madura) in mid 2024, proje ...

, 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 Science Biology * Seashell, a hard outer layer of a marine ani ...

environment, OMVS. z/OS UNIX's predecessor was an operating system component called OpenEdition MVS, first implemented in MVS/ESA SP 4.3 and enhanced in MVS/ESA 5.1. OpenEdition MVS initially 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 application programming interfaces (APIs), along with comm ...

standards, but X/OPEN, the predecessor to The Open Group, certified MVS/ESA SP V5.1. IBM continues to enhance UNIX System Services. Typically every release of z/OS includes enhancements to z/OS UNIX.

Notes

References

External links

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

Overview

See also

Notes

References

External links