Editing VSE (operating system) (section)

{{Infobox OS
| name                   = VSE<sup>n</sup>
| logo                   = VSEn Logo.png
| logo caption           = 
| logo size              = 200px
| screenshot             = 
| caption                = 
| developer              = [[21st Century Software]] (previously [[IBM]])
| source_model           = [[Closed source]]
| kernel_type            = 
| supported_platforms    = 
| ui                     = 
| family                 = [[DOS/360 and successors]]
| released               = 
| latest_release_version = 6.3  <!-- If you update this, don't forget to update [[Comparison of operating systems]]--> 
| latest_release_date    = {{Start date and age|2022|05|17}}<ref name="vsen-6.3" />
| latest_test_version    = 
| latest_test_date       = 
| marketing_target       = [[IBM mainframe]] computers
| programmed_in          = 
| prog_language          = 
| language               = 
| updatemodel            = 
| package_manager        = 
| working_state          = Current
| license                = [[Proprietary software|Proprietary]]
| website                = {{URL|21cs.com/vsen/}}
}}
{{History of IBM mainframe operating systems|dos}}
'''VSE<sup>n</sup>''' ('''''V'''irtual '''S'''torage '''E'''xtended'') is an [[operating system]] for [[IBM mainframe]] computers, the latest one in [[DOS/360 and successors|the DOS/360 lineage]], which originated in 1965. It is less common than [[z/OS]] and is mostly used on smaller machines.<ref>{{cite book
|title=Reduce Risk and Improve Security on IBM Mainframes (Volume 1)
|quote=Extended (z/VSE) is popular with users of smaller mainframe computers.
|url=https://books.google.com/books?isbn=0738440108  |isbn=978-0738440101
|author1=Axel Buecker  |author2=Boudhayan Chakrabarty
|author3=Lennie Dymoke-Bradshaw |date=2016}}</ref><ref>{{cite magazine  
|magazine=IBM Systems Magazine
|quote=At the risk of oversimplification, z/VSE is similar to z/OS but relatively smaller, simpler ... cost-effective
|url=http://ibmsystemsmag.com/mainframe/administrator/performance/ahead_of_the_pack
|title=Ahead of the Pack |archive-url=https://web.archive.org/web/20180822113420/http://ibmsystemsmag.com/mainframe/administrator/performance/ahead_of_the_pack/ |archive-date=2018-08-22}}</ref><ref>{{Cite journal|last=Stedman|first=Craig|date=29 Jan 1996|title=IBM teaches VM, VSE new mainframe tricks|url=https://books.google.com/books?id=RC7GmaXkP9YC&pg=PT32|journal=Computerworld|volume=30|issue=5|pages=39}}</ref>

DOS/VSE was introduced in 1979 as a successor to DOS/VS; in turn, DOS/VSE was succeeded by VSE/SP version 1 in 1983, and VSE/SP version 2 in 1985.<ref name="HoskinsFrank2003">{{cite book|author1=Jim Hoskins|author2=Bob Frank|title=Exploring IBM Eserver Zseries and S/390 Servers: See Why IBM's Redesigned Mainframe Server Family Has Become More Popular Than Ever|url=https://books.google.com/books?id=NtHhpIjIFMEC&pg=PA275|year=2003|publisher=Maximum Press|isbn=978-1-885068-91-0|page=275}}</ref> In the late 1980s, there was a widespread perception among VSE customers that IBM was planning to discontinue VSE and migrate its customers to [[MVS]] instead, although IBM relented and agreed to continue to produce new versions of VSE.<ref>{{Cite journal|last=Cortese|first=Amy|date=21 Aug 1989|title=Militant VSE users upbeat but impatient|url=https://books.google.com/books?id=_reJxWK0KD4C&pg=PA17|journal=Computerworld|volume=23|issue=34|pages=17}}</ref><ref>{{Cite journal|last=Ambrosio|first=Johanna|date=23 Jul 1990|title=VSE gets jumpstart with sequel|url=https://books.google.com/books?id=0bqdMvDMv74C&pg=PA6|journal=Computerworld|volume=24|issue=30|pages=6}}</ref> In February 2005, IBM announced z/VSE as successor to VSE/ESA 2.7, which was named to reflect the new [[System z]] branding for IBM's mainframe product line.<ref>{{cite web
|quote=z/VSE continues the focus on interoperability that began with VSE/ESA Version 2 Release 5, and continued with VSE/ESA Version 2 Release 6 and VSE/ESA Version 2 Release 7
|url=https://www.ibm.com/common/ssi/fcgi-bin/ssialias?subtype=ca&infotype=an&appname=iSource&supplier=897&letternum=ENUS205-014
|title=IBM z/VSE V3.1 generally available 
| website=[[IBM]] |date=February 1, 2005}}</ref><ref name=Forb.Z>{{cite magazine |magazine=Forbes  |date=January 13, 2015
|quote=The new system — called IBM z13 and running the fastest ... this latest revision of IBM's time-hallowed product line incorporates new ... fast enough to intervene in time to avert brand damage and lost sales? Well ... What used to be "System z" is now "z Systems," with the current product being the IBM z13.
|url=https://www.forbes.com/sites/rogerkay/2015/01/13/with-z-systems-refresh-ibm-reminds-us-that-mainframes-remain-relevant
|title=With Z Systems Refresh, IBM Reminds Us That Mainframes Remain Relevant
|author=Roger Kay}}</ref> In June 2021, 21st Century Software Inc announced that it had licensed the z/VSE source code from IBM with the intention of developing new versions of the operating system.<ref>{{cite web|url=https://www.21stcenturysoftware.com/license-z-vse-code-from-ibm/|title=21st Century Software Technologies, Inc. Enters Agreement to License z/VSE Operating System and Middleware Stack From IBM|author=Rebecca Levesque|date=2021-06-01|access-date=2022-06-09|website=21st Century Software}}</ref> As part of this transfer, z/VSE was renamed to VSE<sup>n</sup>.<ref name="vsen-6.3">{{cite web|url=https://www.21stcenturysoftware.com/21st-century-software-announces-vsen-v6-3/|title=21st Century Software Announces VSEn V6.3|author=Lisa Klemens|date=2022-03-25|access-date=2022-06-09}}</ref>