25.4.2.1 Enforcing Installation Standards

You will continue to refine the standards developed above, and should use RACF to protect critical resources. You can also use installation exits to enforce standards not controlled by RACF, but keep in mind that it is often easier to enforce them through other procedures.

25.4.2.2 Implementing System Security

OS/390 users have access to all data sets in the system unless specifically restricted via the security product. Intentional or unintentional modification of system data sets can compromise system availability.

You should use RACF (now called the OS/390 Security Server) to protect critical resources such as system data sets, catalogs, and access to valuable, sensitive or confidential data. You should identify all users of the system, whether they are TSO, on-line, batch job owners, or console operators.

Security (RACF) can also be used to enforce the installation standards. See Appendix D ªSecurity for System Data Setsº inOS/390 Security Server (RACF) Security Administrator, SC28-1915.

See the following RACF books for more information:

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OS/390 Security Server (RACF) Introduction, GC28-1912

OS/390 Security Server (RACF) Planning: Installation and Migration,

GC28-1920

OS/390 Security Server (RACF) General User¢s Guide, SC28-1917

MVS 3.1.3 and RACF 1.9 Security Implementation Guide, GG24-3585

RACF V2.2 Installation and Implementation Guide, SG24-4580

25.4.2.3 Backing Up Your System

Periodic system backups are critical to maintaining access to critical resources and protecting your investments in systems programming and migration efforts. You should take full-volume dumps of all system packs except paging data sets, and JES2 spool and checkpoint volumes. This should be part of your SMS strategy, and developed early in the project along with your disaster recovery goals and requirements.

25.4.2.4 Creating an Emergency Backup System

As careful as you are, there may be a time that you can not IPL your OS/390 system because the IPL text in the SYSRES is damaged, the master catalog is deleted, or the JES2 procedure has a JCL error. (There are many other reasons why you may not be able to IPL.)

In any case, you should have a backup OS/390 system that you can IPL to diagnose and fix the problem. Many installations have a simple one or two-pack MVS system that can support a TSO user and a few batch jobs. Another strategy is to use your system maintenance environment to provide a simple but usable backup system. There are also vendor products such as SAE, which provide ²rescue² systems.

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IBM OS/390 manual Enforcing Installation Standards, Implementing System Security, Backing Up Your System
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OS/390 specifications

IBM OS/390, a versatile operating system, was a cornerstone in enterprise environments and played a pivotal role in mainframe computing. Released in the mid-1990s, OS/390 combined the strengths of IBM's MVS (Multiple Virtual Storage) with new features and enhancements, targeting scalability, reliability, and performance in demanding business applications.

One of the key features of OS/390 was its robust support for multiple users and processes. The system allowed thousands of concurrent users to access applications and data, ensuring high availability and minimizing downtime—a critical requirement for many large organizations. This scalability was supported through various enhancements in memory management and processor scheduling, enabling optimal resource allocation across diverse workloads.

OS/390 was known for its superior workload management capabilities. The Workload Manager (WLM) component allowed administrators to define service policies, specifying how system resources would be allocated according to the priority of tasks. This ensured that critical business processes received the necessary resources while less critical tasks were managed more flexibly.

Another significant characteristic of OS/390 was its commitment to security. The operating system provided comprehensive security features, including user authentication, data encryption, and auditing capabilities. This focus on security was vital for organizations handling sensitive data, ensuring compliance with regulations and safeguarding against unauthorized access.

OS/390 also supported advanced technologies that facilitated integration and development. The system included features like the IBM CICS (Customer Information Control System) for transaction processing and IMS (Information Management System) for database management. These technologies allowed organizations to build robust, high-performance applications tailored to specific business needs.

The ease of network integration was another strength of OS/390. With the advent of the Internet and global connectivity, OS/390 systems could easily interface with various network protocols, enabling businesses to operate in a connected world. This inclusion paved the way for many organizations to expand their capabilities and offer new services, driving digital transformation.

In conclusion, IBM OS/390 represented a significant advancement in mainframe technology, combining scalability, security, and robust workload management. Its rich feature set and support for critical enterprise applications solidified its role as a vital component of many organizations' IT infrastructures, ensuring they could meet their operational challenges head-on while supporting future growth. As technology continues to evolve, the legacy of OS/390 remains influential in the realm of computing.
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