Editing Z/OS (section)

{{short description|64-bit operating system for IBM mainframes}}
{{redirect|ZOS|the Canadian television miniseries|ZOS: Zone of Separation|the airport|Cañal Bajo Carlos Hott Siebert Airport}}
{{Tone|date=March 2021}}
{{Lowercase title}}
{{Infobox OS
| name = z/OS
| logo = IBM logo.svg
| logo caption = 
| logo size = 120px
| screenshot = <!-- Deleted image removed:  [[File:ZOS welcome screen.png|300px]] -->
| caption = The z/OS welcome screen as seen through a [[terminal emulator]]. This classic interface is still available but [[World Wide Web|Web]] access is common.
| developer = [[IBM]]
| family = {{hlist|[[MVS]]|[[Unix]]}}
| source_model = [[Closed source]] with [[open source]] components
| released = {{Start date and age|2001|03|30}} (V1R1, announced October, 2000)
| latest_release_version = Version 3.1 (V3R1)
| latest_release_date = {{Start date and age|2023|09|29}}
| latest_test_version = 
| latest_test_date = 
| marketing_target = Enterprise / Mainframes
| programmed_in = primarily [[PL/X]], [[HLASM]], and [[C (programming language)|C]]/[[C++]]<ref>{{cite web|last1=Giorgio|first1=Anthony|title=We are the IBM z/OS development team. AUA! • r/IAmA|url=https://www.reddit.com/r/IAmA/comments/3f5x1i/we_are_the_ibm_zos_development_team_aua/ctlnqje/?context=1|website=reddit|date=30 July 2015|access-date=19 June 2017|language=en}}</ref>
| prog_language = [[Java (programming language)|Java]], [[C (programming language)|C]], [[C++]], [[COBOL]], [[PL/I]], [[HLASM]], [[FORTRAN]], [[REXX]], and many others
| language = [[English language|English]] and other languages
| kernel_type = [[Monolithic kernel|Monolithic]] (uniquely hardware-assisted)
| userland = MVS, [[UNIX System Services]]
| ui = [[ISPF]], z/OS Management Facility
| license = [[Proprietary software|Proprietary]] monthly license charge (MLC); pricing available based on actual use (VWLC, EWLC, AWLC, EAWLC, IWP); reduced pricing options (zELC, zNALC, "Solution Edition") for many applications
| working_state = Current
| supported_platforms = [[z/Architecture]]
| updatemodel = 
| package_manager = [[SMP/E]]
| website = {{URL|ibm.com/products/zos}}
}}
{{History of IBM mainframe operating systems|os_only=os_only}}

[[File:IBM System z10.jpg|thumbnail|An IBM System Z10 mainframe computer on which z/OS can run.]]

'''z/OS''' is a [[64-bit computing|64-bit]] [[operating system]] for [[IBM]] [[z/Architecture]] [[Mainframe computer|mainframes]], introduced by IBM in October 2000.<ref>Vijayan, Jaikumar. "Z/OS: Users Expect Big Savings." ''[[Computerworld]],'' 19 November 2001, Vol. 35 Issue 47, p. 40</ref> It derives from and is the successor to [[OS/390]], which in turn was preceded by a string of [[MVS]] versions.<ref group="NB">Starting with the earliest:

* OS/VS2 Release 2 through Release 3.8
* MVS/System Extensions (MVS/SE)
* MVS/System Product (MVS/SP) Version 1
* MVS/System Product Version 2 (MVS/Extended Architecture, [[MVS/XA]])
* MVS/System Product Version 3 (MVS/Enterprise Systems Architecture, MVS/ESA)
* MVS/ESA SP Version 4
* MVS/ESA SP Version 5
</ref> Like OS/390, z/OS combines a number of formerly separate, related products, some of which are still optional. z/OS has the attributes of modern operating systems but also retains much of the older functionality that originated in the 1960s and is still in regular use—z/OS is designed for [[backward compatibility]].