Editing VSE (operating system)

{{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>

==Overview==
DOS/360 originally used [[24-bit computing|24-bit]] addressing. As the underlying hardware evolved, VSE/ESA acquired [[31-bit computing|31-bit]] addressing capability.<ref name=Ent24.64>{{cite web  |website=EnterpriseSystemsMedia.com
|url=http://enterprisesystemsmedia.com/article/virtual-addressing-with-z-vse-from-24-bit-to-64-bit
|title=Virtual Addressing With z/VSE: From 24-Bit to 64-Bit
|author=Ingolf Salm  |date=May 7, 2012}}</ref>

IBM released z/VSE Version 4, which requires [[64-bit computing|64-bit]] [[z/Architecture]] hardware and can use 64-bit real mode addressing, in 2007. With z/VSE 5.1 (available since 2011)<ref name=Ent24.64/> z/VSE introduced 64-bit virtual addressing and memory objects (chunks of virtual storage), that are allocated above 2&nbsp;GB.

==User interfaces==
===Job Control Language (JCL)===
A [[Job Control Language]] (JCL) that continues in the [[DOS/360 and successors#Job control|positional-parameter orientation of earlier DOS systems]] is VSE<sup>n</sup>'s [[batch processing]] primary user interface.<ref>{{cite web
|title=Introduction to the New Mainframe: IBM z/VSE Basics
|url=https://www.redbooks.ibm.com/redbooks/pdfs/sg247436.pdf
|date=March 1, 2016}}</ref><ref>{{cite web
|url=https://docops.ca.com/display/IDMS19/Storage%2BConsiderations%2BFor%2Bthe%2BBatch%2BExternal%2BInterface
|title=Storage Considerations For the Batch External Interface}}</ref> There is also another, special interface for [[system console]] operators.<ref>{{cite web 
|title=Hints and Tips for z/VSE 5.2
|url=http://public.dhe.ibm.com/eserver/zseries/zos/vse/pdf3/zvse52/hintdmm2.pdf}}</ref>

===Beyond batch===
VSE<sup>n</sup>, like z/OS systems, had traditionally provided [[3270 terminal]] user interfaces. However, most VSE<sup>n</sup> installations have at least begun to add [[Web browser]] access to VSE<sup>n</sup> applications. VSE<sup>n</sup>'s [[Internet protocol suite|TCP/IP]] is a separately priced option for historic reasons, and is available in two different versions from two vendors. Both vendors provide a full function TCP/IP stack with applications, such as telnet and [[FTP]]. One TCP/IP stack provides IPv4 communication only, the other IPv4 and IPv6 communication. In addition to the commercially available TCP/IP stacks for VSE<sup>n</sup>, IBM also provides the Linux Fastpath method which uses [[IUCV]] socket or [[Hipersockets]] connections to communicate with a Linux guest, also running on the mainframe.

Using this method the VSE<sup>n</sup> system is able to fully exploit the native Linux TCP/IP stack.<ref>{{cite web|url=http://enterprisesystemsmedia.com/article/the-z-vse-fast-path-to-linux-on-system-z|title=The z/VSE Fast Path to Linux on System z|access-date=2013-10-16|archive-date=2013-10-22|archive-url=https://web.archive.org/web/20131022233654/http://enterprisesystemsmedia.com/article/the-z-vse-fast-path-to-linux-on-system-z|url-status=dead}}</ref>

IBM recommends<ref name=Recommends>{{cite web
|quote=Both z/VSE and Linux on IBM Z run as z/VM Guests in the same z/VM-mode LPAR .... The use of a z/VM-mode LPAR is recommended.
|url=http://public.dhe.ibm.com/eserver/zseries/zos/vse/pdf3/wavv13/LinuxFastPath.pdf
|title=z/VSE Fast Path to Linux on IBM Z}}</ref> that z/VSE customers run [[Linux on IBM Z]] alongside, on the same physical system, to provide another 64-bit application environment that can access and extend z/VSE applications and data via [[Hipersockets]] using a wide variety of [[Middleware (distributed applications)|middleware]]. [[CICS]], one of the most popular enterprise [[transaction processing system]]s, is extremely popular among VSE<sup>n</sup> users and now implements recent innovations such as [[Web services]]. [[IBM Db2|Db2]] is also available and popular{{Clarify|date=October 2020}}.

==Device support==
VSE<sup>n</sup> can use ECKD, FBA and SCSI devices. [[Fibre Channel]] access to SCSI storage devices was initially available on z/VSE 3.1 on a limited basis (including on IBM's [[Enterprise Storage Server]] (ESS), IBM System Storage [[DS8000]], DS6000 series), but the limitations disappeared with 4.2 (thus including [[IBM Storwize V7000]], V5000, V3700 and V9000).<ref>{{cite web
|url=http://public.dhe.ibm.com/s390/zos/vse/pdf3/zVSE_SCSI_and_Migration_Whitepaper.pdf
|title=z/VSE SCSI Support and Migration Options}}</ref>

==See also==
* [[z/OS]] 
* [[z/TPF]]
* [[z/VM]]
* [[History of IBM mainframe operating systems#DOS/VS]]
* [[History of IBM mainframe operating systems]]

==References==
{{Reflist}}

==External links==
*[https://21cs.com/vsen/ VSE<sup>n</sup> website]

{{IBM operating systems}}

{{DEFAULTSORT:VSE}}
[[Category:IBM mainframe operating systems]]