5650-ZOS IBM z/OS V2.3

IBM Europe Sales Manual
Revised:  March 05, 2019.

Table of contents
TOC Link Product life cycle dates TOC Link Description
TOC Link Program number TOC Link Operating environment
TOC Link Abstract TOC Link Planning information
TOC Link Product positioning TOC Link Publications
TOC Link Highlights TOC Link Security, auditability, and control


Product life cycle dates

Program NumberVRM Announced Available Marketing Withdrawn Service Discontinued
5650-ZOS02.03.002017/07/172017/09/29 - -
5650-ZOS02.02.002015/07/282015/09/30 2018/01/29 -
5650-ZOS02.01.002013/07/232013/09/30 2016/01/252018/09/30

Back to topBack to top

Program number

  • IBM z/OS V2.3.0 (5650-ZOS)

Back to topBack to top


IBM's z/OS V2.3 operating system continuously delivers innovations designed to build and improve the highly scalable and securable next- generation infrastructure needed. IBM z/OS V2.3 delivers the performance, availability, scale, I/O support, and security to provide this infrastructure, giving businesses the ability to instantly react to opportunities.

z/OS is designed to support companies' most mission-critical work while meeting stringent service levels, illustrated by clients that include the world's leading banks, financial services companies, healthcare enterprises, and governments. Focusing on three critical areas, security, simplification, and cloud, z/OS V2.3 enables extensive encryption of data, helps simplify the overall management of the z/OS ecosystem to increase productivity, and provides a simple, consumable approach for self-service provisioning and rapid delivery of software-as-a-service, helping companies to leverage the API economy.

IBM z/OS V2.3 updates (announced March 5, 2019)

This z/OS V2.3 announcement delivers the following new capabilities:

  • Multiple installation support for Network Configuration Assistant to enable you to install multiple configuration files in a single action
  • Web Enablement Toolkit support for Unicode character set in the JSON parser that enables you to now parse and perform various other services on JSON text in Unicode
  • Web Enablement Toolkit support for new JSON search scope that can greatly improve the performance cost of searching JSON
  • Unicode Services support for composition characters on both sides of a user-defined conversion table that will help clients to implement solutions which meet certain regional IT standards associated with surnames and first names on z/OS V2.2 and V2.3
  • New default behavior for terminating signals in Language Environment-enabled applications that enables resource managers, RRS, or Context Services exits to no longer commit in-progress updates
  • z/OSMF enhancements:
    • Ability to search, browse, and edit data sets from the z/OSMF UI as well as create shortcuts for data sets in a z/OSMF desktop or folder.
    • An OpenAPI document for z/OS Jobs REST APIs and z/OS data set and file REST APIs.
    • The z/OSMF Workflows task will be enhanced so users can export a workflow as a printable format that contains a front cover, front matter, back matter, or back cover.
  • IBM Cloud Provisioning and Management for z/OS enhancements:
    • System programmers will be able to view memory consumed by software service instances that are provisioned by a specific tenant and set a cap for memory consumption.
    • Clustered composite templates enable you to leverage sysplex capability to provision a continuously available middleware environment.
    • When you create a cloud provisioning template, you will be able to specify files for a template, such as the workflow and actions definition files in sequential or partitioned data sets. Previously, they were required to be z/OS UNIX files.
    • The Workflow Editor includes a "toolbox" of IBM-supplied steps, which are designed for performing common tasks on z/OS, such as creating a data set or submitting a REST request.
  • New XL C/C++ compiler that uses the Clang (C language family) infrastructure from the LLVM open source community for a portion of the compiler to provide support for the C11 and C++11 language standards
  • New look and linking for product documentation PDFs

IBM z/OS V2.3 updates (announced November 13, 2018):

This z/OS V2.3 announcement delivers the following new user experience, security, data protection, application development, and software installation capabilities:

  • Simplify and modernize the user experience to enhance productivity:
    • z/OSMF, the modern web interface for z/OS, has been enhanced for easier use and expanded capabilities in several areas, including workflows and sysplex management.
  • Enhanced security and data protection:
    • Ease-of-use improvements and stronger security technology have been delivered in the Integrated Cryptographic Service Facility (ICSF). ICSF helps protect data that is stored within a system, in a file on magnetic tape off a system, and sent between systems from unauthorized disclosure or modification.
    • A new z/OSMF plug-in called the zERT Network Analyzer is now available to visually determine which z/OS TCP and Enterprise Extender traffic is or is not cryptographically protected.
  • Improving and simplifying application development:
    • Container Pricing for IBM Z, providing simplified and transparent software pricing for qualified solutions, allowing broader application deployment on Z at a competitive price
    • An upgraded version of X-Windows virtual framebuffer (Xvfb), enabling a client to run graphical applications without a physical display device
    • Numerous improvements to simplify use of the Network File System (NFS), UNIX System Services, z/OS Web Enablement Toolkit, program management binder, and the Language Environment:
      • New function in the z/OS NFS Server allows for the sharing of compressed data sets.
      • Iconv utility enhancements when converting data from Unicode to other CCSIDs.
      • Potential to reduce the size of the program object or load module with the program management binder enhancement.
      • Enhanced authentication support for the Web Enablement Toolkit HTTP proxy function.
      • Serviceability enhancement to Language Environment Dumps.
    • Improvements that simplify z/OS platform software installation for the Z ecosystem:
      • IBM intends to help drive z/OS platform-wide improvements in installation and deployment, along with functions that are intended to enable other software vendors to use them.

    IBM z/OS V2.3 updates (announced August 7, 2018)

    This z/OS V2.3 update offers new capabilities designed to support:

    • Simplify and modernize the user experience to enhance productivity
      • IBM z/OSMF
      • New short name for IBM Configuration Assistant for z/OS Communications Server
      • Network Configuration Assistant support for multiple location TCP/IP configuration
    • Enhancing availability, scalability, and performance
      • IBM zHyperWrite data replication
      • zlsof extended processing information
    • Enhanced security and data protection
    • MCS passphrases
  • Improved content delivery
    • Obtaining z/OS content for IBM Knowledge Center
    • IBM z/OS Search Scope Catalog
    • IBM Z: Look@ Knowledge Center message lookup facility
    • z/OS V2.3 Font Collection element
  • Enhanced code page support
    • Code page enhancements for CSSMTP
    • NFS Server Unicode support
  • Improving application development
    • VSAMDB
    • JSON text-rendering sample program
    • JSON entry deletion
    • cp utility enhancements
    • True random number generation for z/OS UNIX

IBM z/OS V2.3 updates (announced April 30, 2018)

This z/OS V2.3 update offers new capabilities designed to support:

  • IBM z/OSMF
  • IBM Cloud Provisioning and Management for z/OS
  • z/OS Communication Server's Inbound Workload Queuing (IWQ) support for QDIO interfaces
  • Installation for IBM z14 Model ZR1

IBM z/OS V2.3 updates (announced March 6, 2018)

This z/OS V2.3 update offers new capabilities designed to support:

  • User key common requesters
  • NFS Server: Encryption
  • IBM z/OSMF
  • RMF

IBM's z/OS V2.2

IBM's z/OS V2.2 operating system and the IBM z13 server work together to deliver innovations designed to help you build the next- generation infrastructure you need. Together, they offer the capacity, scale, availability, and throughput required to help improve business performance, meet response time objectives, protect sensitive data and transactions, and deliver an exceptional customer experience.

IBM z/OS V2.2 updates (announced May 2, 2017)

This z/OS V2.2 update offers new capabilities designed to support:

  • Metering and capping
  • IBM Cloud Provisioning and Management for z/OS

Back to topBack to top

Product positioning

Product positioning - Globalization


z/OS Version 2 is designed to continue to meet a number of important standards. In addition to maintaining previously announced support in z/OS Version 1 for a number of industry standards such as RFCs and PCI-DSS, and adding support for a number of additional standards in z/OS V2.1, these include:

  • z/OS Version 1 earned the IPv6 Phase 2 Ready logo and USGv6 Profile Version 1.0 (NIST SP500-267) certification. z/OS V2.3 Communications Server is designed to meet these standards.
  • The programming interfaces provided by z/OS V2.3 Unicode Services are designed to meet the Unicode 9.0 standard.
  • IBM z/OS V2.1 has been certified as meeting the requirements of the German Common Criteria Certification Body (BSI) Operating System Protection Profile (OSPP) at EAL 4+.
  • IBM plans to pursue an evaluation to the Federal Information Processing Standard (FIPS) 140-2 using National Institute of Standards and Technology's (NIST) Cryptographic Module Validation Program (CMVP) for the System SSL component of the Cryptographic Services element of z/OS. This is intended to help satisfy the need for FIPS 140-2 validated cryptographic functions when using z/OS Communications Server capabilities such as AT-TLS and protocols such as TN3270 and FTP when secured using AT-TLS.
  • IBM also plans to pursue an evaluation to the Federal Information Processing Standard (FIPS) 140-2 using National Institute of Standards and Technology's (NIST) Cryptographic Module Validation Program (CMVP) for the ICSF component of the Cryptographic Services element of z/OS. This is intended to help satisfy the need for FIPS 140-2 validated cryptographic functions by various IBM software products and customer applications running on z/OS.

Back to topBack to top


  • Exploits the latest IBM z14 (z14), supporting up to 170 configurable processors
  • Enhanced data security by extending encryption to the data set level and Coupling Facility structures
  • Simplified end-to-end z/OS management with z/OSMF
  • Tools to simplify management of sysplex infrastructure and new cloud management capabilities
  • Real-Time SMF Analytics infrastructure support
  • Enhancements to zFS file system for uninterrupted operations
  • Increased JES2 resiliency

Back to topBack to top


New approach to encryption

At the core of every enterprise lies data representing core business assets, which if lost or compromised can cause irreparable damage. This core business data may fall within the scope of various regulatory requirements that can govern how it can be used and mandated actions to be taken in the event of loss or inadvertent disclosure.

This has changed the perspective about how core business data should be handled and protected. The use of strong encryption is one of the most impactful ways to reduce risk and financial loss arising from unauthorized access to data. It helps you meet complex compliance mandates by creating a fortified perimeter around core business data. Establishing this perimeter has become more practical and z/OS V2.3 together with z14 can drive pervasive encryption efforts within an enterprise.

z/OS is designed to provide new policy-based pervasive encryption options that take full advantage of the improvements in the z14 platform and can help you build that intrinsic, fortified perimeter around your critical business data. These new capabilities include:

  • Enhanced data protection for many z/OS data sets, zFS file systems, and Coupling Facility list structures give users the ability to encrypt data without needing to make costly changes to applications to imbed encryption APIs within applications.
  • New z/OS policy controls make it possible to use pervasive encryption to protect user data and simplify the task of compliance.
  • z/OS Communications Server includes encryption-readiness technology to enable z/OS administrators to determine which TCP and Enterprise Extender traffic patterns to and from their z/OS systems meet approved encryption criteria and which do not.
Simplify and modernize the user experience to enhance productivity

Clients are faced with a mixed skills workforce composed of professionals who are new to z/OS and those who are already skilled in z/OS. z/OS V2.3 will simplify and modernize the user experience and help make pertinent information readily available and easily accessible:

  • In z/OS V2.3, z/OSMF will be started during the z/OS IPL process. This helps to ensure that z/OSMF services, such as notification services, are present for exploiters of z/OSMF.
  • Continuing to lay the foundation for installation improvements through enhancements to the software packaging and installation capabilities in z/OSMF that provide the basis for a common installer.
  • A new z/OSMF plug-in, Sysplex Management, provides detailed views of sysplex infrastructure resources such as sysplexes and z/OS systems, CFs and CF structures, CF structure connectors, couple data sets and policies, and coupling links.
Transform from an IT cost center to a value-generating service provider

As the API economy develops, customers are incented to move their IT operations from a cost center model to a revenue-generating profit center model. The z/OS platform, known for its outstanding vertical scalability and speed, coupled with leading-edge security and reliability, provides the foundational capabilities that are ideal for private cloud service delivery:

  • z/OSMF will support workflow extensions for IBM Cloud Provisioning and Management for z/OS.
  • z/OS V2.3 delivers Real-Time SMF Analytics infrastructure support, which will enable faster processing for high-volume SMF data, providing the response time required for real-time analysis of SMF data in analytics and cloud applications.

Enabling the z/OS platform with these cloud capabilities delivers innovations not only in certain infrastructure elements and components of the z/OS operating system, but also in selected levels of various z/OS software subsystems such as IBM CICS Transaction Server for z/OS, IBM IMS for z/OS, IBM DB2 for z/OS, IBM MQ for z/OS, and IBM WebSphere Application Server for z/OS.

IBM z/OS V2.3 leverages the IBM z14 capabilities

New functions in z/OS V2R3 continue to enhance the role of IBM Z, with support for the IBM z14 and its role in helping you provide solutions for a trusted digital economy. Capabilities designed to optimize high availability, performance, security, and operational flexibility can help organizations grow and to secure their most critical transaction environments.

In addition to base processor support, z/OS provides the support for these IBM z14 functions and features:

  • Improved cryptographic capabilities that can be leveraged to begin implementation of IBM's pervasive data encryption strategy
  • The IBM zHyperLink Express feature
  • Asynchronous Memory Clear using System Assist Processors (SAPs)
  • Additional new I/O attachment options including the OSA-Express6S, RoCE Express2, and FICON Express 16S+ features
  • Coupling Facility Level (CFLEVEL) 22 and new Coupling link features
  • The Guarded Storage Facility, exploited by IBM SDK for z/OS, Java Technology Edition, Version 8 (5655-DGG)
  • The Instruction Execution Protection Facility
  • IBM Virtual Flash Memory
Improved cryptographic capabilities

z14 provides cryptographic performance improvements with the Crypto Express6S (#0893) and the IBM Z processor-based cryptography with the CP Assist for Cryptographic Functions that helps enable the protection of data in flight or at rest. The Crypto Express6S coprocessor with CCA 6.0 is designed to comply with the Payment Card Industry (PCI) Pin Transaction Security (PTS) Hardware Security Module (HSM) Standard.

The Crypto Express6S compliance with PCI PTS HSM and with CCA 6.0 introduces several new capabilities both for PCI PTS HSM compliance mode and for general use:

  • A new derived key hierarchy so that PCI PTS HSM compliance-tagged key tokens may be used alongside existing keys and services in a nondisruptive fashion with existing master keys.
  • Nondisruptive transition to PCI PTS HSM mode using TKE 9.0.
  • Secure Audit Log hosted from the Crypto Express6S coprocessor with CCA 6.0.
  • Secure public key infrastructure, native X.509 certificate support including PKCS #10 certificate request generation through a new PKI hosted from the coprocessor.
  • Migration planning assistance through active application reporting.
  • CPACF exportable AES cipher key support added for AES cipher keys created using new options in CCA 6.0.
Scalability, availability, and performance

The z14 platform is designed to scale up and out. z/OS V2.3 continues to support the highest levels of scalability and availability to meet service requirements for traditional workload growth as well as new computing initiatives. For instance, the qualities of service, workload isolation, and security of z/OS are designed to support your transformation to private cloud or other platform-as-a-service solutions.

For instance:

  • z/OS V2.3 with z14 processors supports up to 4 TB of available Redundant Array of Independent Memory (RAIM) real memory per server to help improve transaction response times, lower CPU costs, simplify capacity planning, enlarge in-memory buffer pools, helping you improve performance of DB2, WebSphere MQ, batch, SAP and other workloads.
  • Economies of scale with next-generation multithreading (SMT) for zIIP eligible workloads, new support for the I/O System Assist Processor (SAP), 2x AES performance over IBM z13 (z13), a True Random Number Generator, SHA3 support, and RSA/ECC acceleration.
  • FICON Express16S+ is designed with a boost in I/O rates and a reduction in single stream latency to help absorb large application and transaction spikes driven by large unpredictable analytic and mobile workloads.
  • Optimized z/OS Platform for Apache Spark.
  • Java performance: Support for reducing program pauses during Java Garbage Collection.
  • IBM Virtual Flash Memory is the replacement for the Flash Express features, offering up to 6.0 TB of virtual flash memory in 1.5 TB increments for improved application availability and to handle paging workload spikes.
  • IBM zHyperLink Express uses a direct connect short distance link (zHyperLink) to deliver low latency connectivity between z14 and FICON storage systems. Working in conjunction with your existing FICON SAN infrastructure, zHyperLink Express delivers the next generation of I/O for IBM Z storage.
Excellence in workload management and resource optimization

With the ability to intelligently manage workloads, allocate system resources to applications quickly and efficiently and dynamically provision additional server capacity according to policy, z/OS and IBM Z can handle workload spikes to allow you to better meet business needs. With IBM z/OS Workload Manager (WLM) you can manage the processing of mixed diverse workloads to meet business response time goals. WLM can be used to manage service across the entire Parallel Sysplex to provide a single point of control, and is designed to eliminate the need for individual image management.

  • z/OS V2.3 allows shorter Workload Management response time goals. WLM is designed to allow goal definitions for average and percentile response time goals down to 1 ms. z/OSMF RMF is designed to report these shorter response times.
  • z/OS V2.3 will enhance Workload Manager (WLM) to support Tenant Resource Groups (TRGs) as a way to group work, with the ability to independently measure and cap such groups. For example, customers can classify a group of address spaces and instruct WLM to limit ("cap") CPU consumption related to that group, to a limit also specified in the WLM service definition. Similarly, the cap can be removed, allowing CPU consumption for that workload to continue unrestrained.
  • WLM will also be designed to record CPU consumption for each Tenant Resource Group, leading to enhanced Resource Measurement Facility (RMF) reporting for the specified workload.
  • z/OS Workload Management provides a control that allows service classes to be defined such that their specialty processor eligible work will not execute on general purpose processors. In addition, WLM resource groups are enhanced to limit the amount of real storage that may be used by the associated service classes. In particular for workloads that exploit this function, such as Apache Spark workloads, this capability provides the ability to specify that all the applications or jobs submitted to a particular Spark cluster do not exceed a specified real memory limit, and that they do not receive help from standard processors when the zIIP is exceeded.
Security and resiliency to help you reduce risk

With today's more-complex supply chains and the proliferation of mobile devices, data security is under more scrutiny than ever. Cloud and mobile computing models strengthen the need for data custody and resilience. z/OS and IBM Z form the ideal hub for securing and auditing your data and transactions through the use of secured authentication, audit, secured access, cryptography, secured networking, and more.

z/OS V2.3 is designed to provide policy-enabled enhanced data protection for z/OS data sets, zFS file systems, and Coupling Facility structures, providing the ability to encrypt data to help strengthen the protection for mission-critical data. These capabilities are designed to help meet compliance and audit requirements.

The z/OS Communications Server includes z/OS Encryption Readiness Technology (zERT) to help z/OS administrators to determine which TCP and Enterprise Extender (EE) traffic patterns to and from their z/OS systems meet approved encryption criteria and which do not.

In z/OS V2.3, RACF introduces the new ZMFCLOUD class. This class is used to define z/OS cloud-related resources, giving z/OS Cloud security administrators the ability to control access to z/OS cloud- related resources.

Simplification making z/OS easy to manage

You need solutions that are easy to manage and operate so that your expert skills can be more optimally deployed. To help meet this challenge, z/OS continues to simplify diagnosis and problem determination, network and security management, as well as overall configuration and operations. These improvements can help shorten time to value through simpler systems management, improved productivity, and more intuitive management using functions that are easier to understand and use.

The z/OS SDSF feature has had a long history in displaying information on system workloads. In z/OS V2.3, The SDSF browser-based UI is updated with new capability aligned with the 3270 UI. SDSF now provides a new user's guide that is designed to provide detailed information for the end user on how to get started with SDSF and how to use the various functions provided as part of SDSF. The new user's guide is available with the rest of the z/OS product documentation. This makes user information easy to search and bookmark, which should improve the user experience with SDSF. SDSF in z/OS V2.3 supports new enhancements in JES2, particularly in the areas of resiliency, providing visibility to reserved space as well as measurements of spool and control block consumption.

z/OSMF, the web browser-based z/OS management interface, is now a required component of z/OS and is expected to be installed and configured on at least one system in every sysplex. z/OSMF is designed to help you more easily manage a mainframe by simplifying day-to-day configuration, administration, and management of z/OS software. This helps extend skills and maximize productivity, allowing you to create a repeatable and more standardized management approach. z/OSMF automation is designed to help reduce the learning curve and extend your skills using modern capabilities like workflows, REST services, graphical interfaces, support for management of non- z/OS software, and more. Its active user assistance helps guide you through tasks, simplifying operations.

New z/OSMF enhancements

z/OSMF has been enhanced to include:

  • A new z/OSMF plug-in, Sysplex Management, provides detailed views of sysplex infrastructure resources such as Parallel Sysplexes and z/OS systems, CFs and CF structures, CF structure connectors, couple data sets and policies, and coupling links.
  • The z/OSMF WEBISPF plug-in is enhanced in z/OS V2.3 to allow single sign-on within a sysplex. This eliminates the need to continuously log on and off as you navigate system to system.
  • z/OS V2.3 z/OSMF contains a new function called Operator Consoles. This function provides an improved visualization of the z/OS operator consoles, including support for multiple systems in a sysplex.
  • z/OS V2.3 adds a new Workflow Editor to z/OSMF to enable you to edit workflows in the UI instead of directly editing XML files.
  • z/OS V2.3 z/OSMF Software Management is designed to enable you to use a common process to download portable format packages from any software vendor that makes them available. This enables you to use common tools to download packages from participating vendors in the same user interface.

For more information on the z/OS Management Facility, see


Enabling application development

z/OS delivers support to enable application development and integration with existing investments. With z/OS, multiple programming environments can be supported concurrently on the same hardware, all while meeting established service levels. Current z/OS V2.3 applications can be extended and modernized in place, leveraging capabilities of the z14 to deliver value without incurring the cost of replacing or rewriting assets.

z/OSMF supports workflow extensions for IBM Cloud Provisioning and Management for z/OS. This includes improvements to jobname creation, job card attributes, REST workflow steps, and a Workflow Editor.

IBM SDK for Java 8 SR5 provides the following enhancements:

  • Pause less Garbage Collection (GC) delivering more consistent response times for large heap, response-time sensitive applications, by reducing GC stop-the-world pause times through exploitation of the z14 Guarded Storage Facility. This new mode is an extension to existing GenCon GC policy, enabled through Xgc:concurrentScavenge. This function requires a z14 processor.
  • IBM Java for z/OS will exploit RMODE64 to place JIT code cache above the bar, enabled by default in IBM SDK for z/OS, Java Technology Edition, Version 8.0.5 (IBM Java for z/OS V8 SR5).
  • Performance and features:
    • General throughput, footprint, and CPU usage/ramp-up improvements for Liberty and analytics workloads

z/OS V2.3 XL C/C++ provides enhancements in the following areas:

  • Usability:
    • Metal C creates new function pointers that can act on environments as well as calling a function to allow similar coding patterns and automatic environment-based calling.
    • Hexadecimal offsets are provided for structure listings. The layout information can then be better compared and analyzed.
    • The DSECT utility creates C structures/unions that align closer to the original assembler DSECT, to give the same size and member offsets as the original DSECT.
    • Exploitation of new z14 instructions; for example, new ARCH(12) and TUNE(12) support exploits new instructions on the z14 processors, including support for the vector float type.
  • Performance: The architecture default is changed to ARCH(10) (zEC12) to align with the minimum hardware level that z/OS V2.3 supports.
  • Security: Stack protection to protect buffers that are susceptible to overflow and to stop returning from functions that detect overwriting.
  • Debugging:
    • Metal C debug data blocks provide information linking the assembly or objects with the debugging data, providing synchronization of these files.
    • The Saved Option String Information (SOSINFO) utility emits options encoded in the PPA blocks to help in diagnosing problems.
    • DWARF debugging information in object files is added to the executable in an area that is not loaded at run time to allow access to both the debug data and executable code within the same file. The dbx utility supports this feature.

z/OS now includes a copy of the IBM WebSphere Liberty for z/OS application server as an element of z/OS. It is licensed for use by approved products and other z/OS elements to reduce the number of instances of WebSphere Liberty that must be maintained. IBM supports this new WebSphere Liberty element in conjunction with the other elements of z/OS that use it. However, this copy of WebSphere Liberty for z/OS is also available for customer use. Such use is not supported and limited to nonproduction purposes on z/OS as outlined in z/OS Licensed Program Specifications.

Support for open standards

z/OS supports a number of languages to develop software. Language Environment is the prerequisite runtime environment for applications generated with the following IBM compiler products:

  • XL C/C++
  • Enterprise COBOL for z/OS
  • Enterprise PL/I for z/OS
  • Java

Some industry standards and protocols that are supported include, at minimum, full or partial implementations:

  • Java
  • XML (z/OS XML System Services)
  • Unicode
  • METAL C facility
  • C language standard
  • Eclipse
  • Web services standards
  • SOAP
  • IPv4, IPv6
  • JIS
    • JIS X 0201, JIS X 0208, and JIS X 0212
  • CIM
  • EMVCo
  • FIPS
  • PKCS #11 #12
  • ISO Common Criteria
  • IETF standards
  • ANSI standards
  • NIST
  • REST
  • Others

Delivering innovations to build the next-generation infrastructure

Today's economy requires organizations to quickly consume, manipulate, and deliver vast amounts of information, extracting business insight while leveraging the capabilities of cloud services. The information must be securely managed, processed, and delivered across the globe. Such a fundamental shift away from traditional processing needs calls for a highly responsive and reliable platform that can support new workloads without impacting service levels of mission-critical work. The enhancements delivered in z/OS V2.3 provide the infrastructure to smoothly transition businesses for this new IT environment.


z/OS delivers compatibility and flexibility to run multiple releases of z/OS together on the same system, or within a multisystem Parallel Sysplex. For example, see the following coexistence capabilities:

  • z/OS V2.1 coexists with: z/OS V1.12, z/OS V1.13, z/OS V2.1, z/OS V2.2 and z/OS V2.31
  • z/OS V2.2 coexists with: z/OS V1.13, z/OS V2.1, z/OS V2.2, z/OS V2.3
  • z/OS V2.3 coexists with: z/OS V2.1, z/OS V2.2, z/OS V2.3

Migration checks and comprehensive migration manuals (in the base of z/OS) can help simplify migrations. The migration checks help determine whether a z/OS migration action is applicable to your system or if a migration action was completed properly. These checks do not perform any migration actions and are intended to be used along with the information in the z/OS migration book to help you create your own migration plan.

For additional information on z/OS migrations, see


Accessibility by people with disabilities

A US Section 508 Voluntary Product Accessibility Template (VPAT) containing details on accessibility compliance can be found on the IBM Accessibility website.

Back to topBack to top

Operating environment

Hardware requirements

z/OS V2.3 runs on these IBM Z family servers:

  • IBM z14
  • IBM z13
  • IBM z13s (z13s)
  • IBM zEnterprise EC12 (zEC12)
  • IBM zEnterprise BC12 (zBC12)

For a complete description of z/OS V2.3 hardware requirements, see z/OS Planning for Installation (GA32-0890) in IBM Knowledge Center.

Software requirements

The z/OS base is a system that can be IPLed. There are no software prerequisites in order to IPL. Specific functions may require additional products not included in the z/OS base, or in the optional features of z/OS. See the z/OS Planning for Installation (GA32-0890) website for a listing of specific software requirements.
Back to topBack to top

Planning information

Customer responsibilities

The customer is responsible for evaluation, selection, and implementation of security features, administrative procedures, and appropriate controls in application systems and communication facilities.


Coexistence, release migration, and fallback

z/OS gives you compatibility and flexibility as you migrate systems in a multisystem configuration by allowing multiple releases of z/OS to coexist. This includes non-Parallel Sysplex and Parallel Sysplex multisystem configurations. Coexistence allows systems within a multisystem configuration to be upgraded to a new release level of z/OS one system at a time. This is contingent on the fact that the release you are migrating to can coexist with the lowest release running in your multisystem configuration.

Note: These statements represent the current intention of IBM. IBM reserves the right to change or alter the Coexistence-Migration-Fallback policy in the future or to exclude certain releases beyond those stated. IBM development plans are subject to change or withdrawal without further notice. Any reliance on this statement of direction is at the relying party's sole risk and does not create any liability or obligation for IBM.

IBM provides the following coexistence, migration, and fallback for z/OS V2.3:

IBM plans to support an n-2 approach, where three consecutive releases are planned to be supported for coexistence, fallback, and migration. For example, where "n" is z/OS V2.3, IBM intends to allow you to upgrade from z/OS V2.2 directly to z/OS V2.3 with full coexistence, migration, and fallback support to maximize the value of your investment, and from z/OS V2.2 to z/OS V2.3 with full coexistence, migration, and fallback support.

Migration forward as well as fallback should be made within the same z/OS releases supported by the coexistence policy.

Table: Coexistence-Migration-Fallback for z/OS V2.3

Release         supported with release in Column 1
----------      ----------------------------------------
z/OS V2.1       z/OS V1.12,(1) z/OS V1.13,(2) z/OS V2.1
z/OS V2.2       z/OS V1.13,(2) z/OS V2.1, z/OS V2.2
z/OS V2.3       z/OS V2.1, z/OS V2.2, z/OS V2.3

  1. z/OS V1.12 end of service was September 30, 2014.

  2. z/OS V1.13 end of service was September 30, 2016.

This consistent coexistence, migration, and fallback policy applies to release migrations for all configurations, whether they are:

  • Single system configurations
  • Individual systems within a multisystem configuration
  • Cases where a simultaneous IPL is used to migrate all systems in a multisystem configuration at the same time

License Metric Change

  • z/OS V2 is only offered with NALC pricing for customers using NALC for z/OS V1 who are using PSLC for their middleware programs. z/OS V2 customers using AWLC or WLC or AEWLC or EWLC pricing for their middleware programs must migrate from NALC to zNALC pricing.
  • All z/OS customers using NALC pricing are encouraged to migrate to zNALC pricing to obtain the zNALC advantages such as sub-capacity pricing for z/OS with zNALC supported by the SCRT reports, lower prices above 45 MSUs, and aggregated pricing across qualified Parallel Sysplexes.

Back to topBack to top


A program directory is supplied automatically with the basic machine-readable material.

To access the unlicensed z/OS product documentation, start at the z/OS Internet Library.

It contains direct links to the following repositories and content:

  • IBM Knowledge Center sections for z/OS V2.3 and other supported releases
  • z/OS V2R3 Library, hosted on Resource Link, to download individual PDFs
  • Adobe Indexed PDF Collection (SC27-8430) to easily conduct offline searches on the z/OS product documentation
  • Collections of IBM Knowledge Center plug-ins, including the z/OS Base and Features KC4z plug-in collection (SK4T-9263), for customers who host their own instances of IBM Knowledge Center for z/OS (KC4z)

PDF collections are provided in the "zip" format that any modern zip utility can process.

The z/OS publications are available at


Licensed documentation

Subsequent updates (technical newsletters or revisions between releases) to the publications shipped with the product will be distributed to the user of record for as long as a license for this software remains in effect. A separate publication order or subscription is not needed.
Back to topBack to top

Security, auditability, and control

Data security and auditability in the z/OS environment are enhanced by the functions available in the optional Security Server for z/OS feature.

Back to topBack to top


(R), (TM), * Trademark or registered trademark of International Business Machines Corporation.

** Company, product, or service name may be a trademark or service mark of others.

Windows is a trademark of Microsoft Corporation.

UNIX is a registered trademark in the United States and other countries licensed exclusively through X/Open Company Limited.

Terms of use

IBM products and services which are announced and available in your country can be ordered under the applicable standard agreements, terms, conditions, and prices in effect at the time. IBM reserves the right to modify or withdraw this Sales Manual at any time without notice. This Sales Manual is provided for your information only. Additional terms of use are located at

Terms of use

© IBM Corporation 2019.

Contact IBM