z/OS 3.1

Basic Information

• Model: IBM z/OS
• Version: 3.1.0 (PID: 5655-ZOS)
• Release Date (General Availability): September 29, 2023
• Minimum Requirements: Requires IBM z hardware z14 and upward (IBM z14, z15, z16, z17).
• Supported Operating Systems: As an operating system, it runs on specified IBM Z mainframe hardware.
• Latest Stable Version: 3.1.0
• End of Support Date: Follows an Enhanced (E) lifecycle policy, providing a minimum of 5 years of support with an optional 3-year extension.
• End of Life Date: Not explicitly stated, but withdrawn from market (End of Marketing) on January 26, 2026.
• Auto-update Expiration Date: Not specified.
• License Type: IBM Customer Agreement (ICA). Charges are eligible for Subcapacity Pricing.
• Deployment Model: On-premise mainframe operating system, designed for integration into hybrid cloud environments.

Technical Requirements

IBM z/OS 3.1 operates on IBM Z mainframe hardware, leveraging its robust architecture for high-performance enterprise computing.

• RAM (Processor Storage):
  • Minimum 8 GB for IPL on a supported IBM server.
  • Minimum 2 GB when running as a z/VM guest or on an IBM z Personal Development Tool (zPDT).
  • Supports up to 16 TB of processor storage per Logical Partition (LPAR).
  • z/OS Management Facility (z/OSMF) requires 8 GB central storage, with 4 GB specifically for the z/OSMF server.
• Processor:
  • Requires z/Architecture (64-bit).
  • Compatible with IBM z14, IBM z15, IBM z16, and IBM z17 servers.
  • Supports IBM Z Integrated Information Processors (zIIPs) for offloading eligible workloads, enhancing performance.
• Storage:
  • Approximately 10,246 cylinders on a 3390 device for target data sets (as of June 2023).
  • Specific components like EzNoSQL require approximately 2000 primary and 500 secondary cylinders for SMF data.
  • Extended format data sets require DASD attached through cached storage controls.
• Display:
  • For TSO/ISPF, a full-screen display terminal supporting 3270 data stream is required.
  • Minimum interactive screen size: 24 lines by 80 characters.
  • Maximum interactive screen size: 62 lines by 160 characters.
• Ports:
  • TCP/IP connection is required for workstation-based tools like Infoprint Port Monitor to communicate with the z/OS host.
• Operating System: IBM z/OS 3.1 is the operating system itself, running natively on IBM Z mainframe hardware.

Analysis of Technical Requirements: IBM z/OS 3.1 is designed for high-end enterprise environments, demanding significant processor storage and leveraging specialized mainframe hardware. The requirements reflect its role in handling mission-critical workloads with high availability and performance. The support for zIIPs highlights its capability to optimize resource utilization and reduce operational costs for eligible workloads. The storage requirements are substantial, indicative of the large datasets and complex applications typically managed on mainframes. Display requirements cater to traditional mainframe interfaces while also supporting modern web-based management through z/OSMF.

Support & Compatibility

• Latest Version: z/OS 3.1.0
• OS Support: Runs on IBM z14, z15, z16, and z17 servers.
• End of Support Date: Adheres to an Enhanced (E) lifecycle policy, guaranteeing a minimum of 5 years of support with an option for a 3-year extension.
• Localization: Not explicitly detailed in public information, but IBM enterprise software typically offers extensive localization options.
• Available Drivers/Dependencies:
  • IBM Semeru Runtime Certified Edition for z/OS, Version 21 (5655-JB1) is the required Java level for z/OS 3.1 components and elements.
  • Applications can continue to use IBM Semeru Runtime Certified Edition for z/OS, Version 17, 11, and 8, provided these versions remain supported.
• Compatibility:
  • Features enhanced COBOL-Java interoperability, allowing 31-bit COBOL applications to call 64-bit Java programs.
  • Supports containerization through IBM z/OS Container Extensions (zCX) and integrates with Red Hat OpenShift.
  • No longer includes JES3; it ships with JES2 only. Organizations using JES3 must migrate to JES2 or license JES3plus from Phoenix Software International.
  • Requires removal of TCPIP link statements and replacement with Interface statements before migration from previous z/OS versions.
  • SDSF internal protection must be replaced with external protection using RACF SDSF classes.
  • If using z/OS Global Mirror, planning for its replacement is necessary before migrating to z/OS 3.1, as new functions for asynchronous replication are focused on DS8000 Global Mirror.

Analysis of Overall Support & Compatibility Status: IBM z/OS 3.1 maintains strong compatibility with current IBM Z hardware generations, ensuring a stable and powerful foundation for enterprise workloads. The enhanced lifecycle policy provides long-term support, crucial for mission-critical systems. The focus on modern development practices is evident through improved COBOL-Java interoperability and robust containerization support, facilitating hybrid cloud strategies. However, significant changes, such as the deprecation of JES3 and specific TCPIP configurations, necessitate careful planning and migration efforts for existing z/OS environments. Managing Java dependencies is also a key consideration, as required versions for z/OS components evolve.

Security Status

• Security Features:
  • Includes an Authorized Code Monitor to guard against potential vulnerabilities.
  • Offers expanded System Recovery Boost solutions and new interfaces for runtime diagnostics and resource monitoring.
  • Enhances SSL/TLS capabilities, including support for TLS 1.3 cached handshakes for faster and more secure connections.
  • Provides advancements in quantum-safe encryption for data at rest and in flight, with simplified crypto interfaces.
  • Features Security Configuration Assistant (SCA) for simplified security management.
  • Integrated Security Services provide base security functions, including Kerberos security services and Generic Security Service Application Programming Interface (GSS-API) functions.
  • Cryptographic Services offer data secrecy, integrity, personal identification, digital signatures, and cryptographic key management, including Integrated Cryptographic Service Facility (ICSF), Open Cryptographic Services Facility (OCSF), and Public Key Infrastructure (PKI) Services.
  • Security Server (RACF) provides robust access control to protected resources.
  • Supports SMF compliance evidence generation (type 1154 records) for TCP/IP stack, FTP daemon, TN3270E Telnet server, and CSSMTP client.
  • Implements FTP server JES access control.
  • Includes enhancements to IBM zERT Network Analyzer for improved network security monitoring.
• Known Vulnerabilities:
  • General vulnerability statistics for IBM z/OS 3.1.0 are tracked.
  • Specific vulnerabilities have been identified in related IBM products that interact with z/OS, such as IBM App Connect Enterprise and IBM Integration Bus for z/OS (CVE-2025-30761, CVE-2025-30754 due to IBM Java SDK) and IBM Data Virtualization Manager for z/OS (CVE-2024-52899, Remote Code Execution). These vulnerabilities pertain to applications running on or interacting with z/OS, rather than the core operating system itself.
• Blacklist Status: No information found regarding a general blacklist status for IBM z/OS 3.1.
• Certifications:
  • Supports compliance standards such as DISA-STIG 8.12 and CIS IBM z/OS with RACF benchmark 1.0.
  • Achieves PCI HSM Compliance for AES and RSA keys.
• Encryption Support:
  • Supports TLS 1.3 and advancements in quantum-safe encryption.
  • Utilizes DES, CDMF, RC 40-bit, RSA, and DSA algorithms via Security Server (RACF).
  • Base Cryptographic Services element supports keys up to 56 bits; longer keys are supported with the optional z/OS Security Level 3 feature.
• Authentication Methods:
  • Leverages Kerberos security services through Integrated Security Services.
  • Employs RACF for robust user authentication and authorization.
• General Recommendations:
  • Regularly monitor processor storage usage to ensure optimal security and performance.
  • Keep Java dependencies current, as specified by IBM, to mitigate potential vulnerabilities.
  • Migrate from SDSF internal protection to external RACF protection.
  • Plan for replacement of z/OS Global Mirror if currently in use, as support for new asynchronous replication functions is shifting.

Analysis on Overall Security Rating: IBM z/OS 3.1 offers a highly secure operating environment, building on the mainframe's long-standing reputation for robust security. Its comprehensive suite of security features, including advanced encryption, strong authentication methods, and continuous monitoring capabilities, addresses modern threat landscapes, including emerging quantum computing threats. Compliance with industry standards and certifications further solidifies its security posture. While specific vulnerabilities may arise in associated software, the core OS provides extensive mechanisms for protection, detection, and compliance, making it a strong choice for environments requiring the highest levels of data integrity and confidentiality.

Performance & Benchmarks

• Benchmark Scores: Specific benchmark scores are not detailed in the provided public information.
• Real-world Performance Metrics:
  • Features an AI-powered Workload Manager (WLM) that intelligently predicts upcoming batch workloads and optimizes system resources accordingly, enhancing efficiency.
  • zIIP enablement can significantly improve z/OSMF performance by offloading eligible workloads.
  • Regression tests for z/OSMF indicate performance levels are almost equivalent to the previous version (z/OSMF V2R5).
  • Designed to facilitate the performance and optimization of supported z/OS hardware.
  • Incorporates functions that reinforce scalability, availability, and network efficiency.
  • Improved performance is noted for z/OS Container Extensions (zCX).
• Power Consumption: Specific power consumption metrics are not detailed in the provided public information.
• Carbon Footprint: Specific carbon footprint metrics are not detailed in the provided public information.
• Comparison with Similar Assets:
  • The update from z/OS 2.5 to 3.1 introduces significant AI capabilities, marking a substantial evolution in the operating system's intelligence and automation.
  • Enhancements aim to optimize mainframe assets for new business innovation and extract value from mission-critical data, suggesting improved efficiency over previous versions.

Analysis of Overall Performance Status: IBM z/OS 3.1 focuses on intelligent performance optimization, primarily through its AI-infused capabilities. The AI-powered Workload Manager is a key innovation, promising proactive resource management and improved efficiency for batch processing. While explicit benchmark scores are not readily available, the emphasis on leveraging AI and zIIPs, alongside continuous enhancements, indicates a strong commitment to maximizing the performance of IBM Z hardware. The system is engineered for high scalability and availability, crucial for enterprise-level operations. The performance improvements in areas like zCX suggest better support for modern, containerized workloads.

User Reviews & Feedback

User reviews and feedback for IBM z/OS 3.1 highlight its strategic advancements in AI, hybrid cloud integration, and security, positioning it as a forward-looking enterprise operating system.

• Strengths:
  • AI-Infused Operating System: Praised for integrating AI capabilities directly into the OS, enabling intelligent automation, accelerated inferencing, and improved system administration.
  • Hybrid Cloud Integration: Designed to simplify data storage and management, integrating mainframe data, operations, and applications with hybrid cloud environments for agility and flexibility.
  • Enhanced Containerization: Strong support for z/OS Container Extensions (zCX) and Red Hat OpenShift is a significant advantage for modernizing applications and development.
  • Stronger Security and Resilience: Users appreciate the continuous focus on security, including new features like the Authorized Code Monitor, improved SSL/TLS, and quantum-safe encryption advancements.
  • Improved Developer Experience: Enhanced COBOL-Java interoperability and advanced DevOps tools are seen as beneficial for mainframe developers.
  • AI-powered Workload Management: The AI-powered WLM is noted for its ability to optimize system resources by predicting batch workloads.
  • Enhanced z/OSMF Functionality: The improvements to z/OS Management Facility are welcomed for simplifying day-to-day operations.
• Weaknesses:
  • Migration Requirements: Requires migration from older IBM z hardware (e.g., z13 and below) to z14 or newer.
  • Configuration Changes: Existing TCPIP link statements must be removed and replaced with Interface statements before migration.
  • Security Configuration Updates: SDSF internal protection needs to be replaced with external protection using RACF SDSF classes.
  • Dependency Management: Java dependencies can change and require careful management to ensure compatibility and security throughout the lifecycle.
  • JES3 Deprecation: The removal of JES3 support means sites using it must migrate to JES2 or acquire JES3plus, which can be a significant undertaking.
  • z/OS Global Mirror Replacement: Users of z/OS Global Mirror need to plan for its replacement due to shifting support for asynchronous replication technologies.
• Recommended Use Cases:
  • Organizations running critical business operations that require high levels of reliability, security, and performance.
  • Environments looking to integrate AI and Machine Learning capabilities directly into their core operating system for intelligent automation and data insights.
  • Enterprises pursuing hybrid cloud strategies that involve leveraging mainframe data and applications in conjunction with cloud platforms.
  • Modernization efforts for existing mainframe applications, particularly those benefiting from enhanced COBOL-Java interoperability and containerization.

Summary

IBM z/OS 3.1 represents a significant evolution in mainframe operating systems, positioning itself as an AI-infused, hybrid cloud-ready platform for critical enterprise workloads. Released on September 29, 2023, it is the latest stable version, requiring IBM z14 or newer hardware and a minimum of 8 GB of processor storage for optimal operation. The operating system adheres to an Enhanced lifecycle policy, ensuring long-term support.

Strengths: The primary strength of z/OS 3.1 lies in its deep integration of Artificial Intelligence and Machine Learning capabilities, including an AI-powered Workload Manager that optimizes resource allocation and an AI Framework for seamless AI integration into z/OS products. This focus on AI enhances intelligent automation and accelerated inferencing, extracting valuable insights from mission-critical data. The system also boasts robust security features, such as an Authorized Code Monitor, advanced SSL/TLS (including TLS 1.3), quantum-safe encryption, and comprehensive cryptographic services, reinforcing the mainframe's reputation for data integrity and confidentiality. Compatibility with modern development practices is improved through enhanced COBOL-Java interoperability and strong support for containerization via z/OS Container Extensions (zCX) and Red Hat OpenShift, facilitating hybrid cloud strategies and application modernization. The enhanced z/OS Management Facility (z/OSMF) further simplifies system administration.

Weaknesses: Adopting z/OS 3.1 requires careful planning, particularly for organizations migrating from older z hardware (pre-z14). Significant configuration changes are necessary, including the removal of TCPIP link statements and the replacement of SDSF internal protection with external RACF protection. The deprecation of JES3 means a mandatory migration to JES2 or a third-party solution (JES3plus) for affected users. Additionally, users of z/OS Global Mirror must plan for its replacement. Managing evolving Java dependencies is also a continuous requirement.

Recommendations: IBM z/OS 3.1 is highly recommended for enterprises seeking to modernize their mainframe environments, integrate AI and machine learning into core business processes, and leverage hybrid cloud models while maintaining the unparalleled security and reliability of the IBM Z platform. Organizations should meticulously plan for the necessary hardware upgrades and software migrations, particularly concerning JES3 and network configurations. Proactive management of Java dependencies and continuous monitoring of security advisories are crucial for optimal performance and security. For those operating mission-critical applications, z/OS 3.1 offers a powerful and intelligent foundation for future growth and innovation.

The information provided is based on publicly available data and may vary depending on specific device configurations. For up-to-date information, please consult official manufacturer resources.