JES2 initialization options described in Chapter 1 of the OS/390 JES2 Initialization and Tuning Guide.

10.2.2.1 The JES2 Procedure

Similar to the POWSTRT procedure, the JES2 member of SYS1.PROCLIB is used to initialize JES2. (It must be in SYS1.PROCLIB, not in any other procedure library.) You must tailor the JES2 proc to include your JES2 load libraries, parameter members, procedure libraries, and other options. For the specific requirements of the JES2 procedure, see Chapter 1 in the JES2 Init & Tuning Guide.

10.2.3 Tailoring JES2

You can customize JES2 for your installation by setting JES2 initialization parameters, issuing JES2 operator commands, or using JES2 supplied exits.

10.2.3.1 JES2 Initialization Parameters

Similar to the VSE/POWER tables assembled with generation macros, JES2 uses a series of initialization parameters to tailor the system. Whereas the POWER macros are assembled and linked into the POWER phases, the JES2 initialization parameters are placed in one or more sequential or partitioned data sets, and pointed to by the JES2 procedure.

See Table 17 on page 226 for a comparison of POWER macros to JES2 initialization parameters.

10.2.3.2 JES2 Operator Commands

Practically everything you can specify in JES2 initialization parameters can also be specified or changed through JES2 operator commands.

See JES2 Commands for details.

See 10.4.3, ªPOWER-JES2 Command Equivalencesº on page231 for a comparison of POWER exits to JES2 exits.

10.2.3.3 JES2 Installation Exits

You can also customize JES2 through any of 49 supplied IBM exits, or modify the JES2 code directly through source modifications or VER/REP statements in the JES2 init deck.

See JES2 Exits and JES2 Job Related Exits for details.

See 10.4.2, ªExit Comparisonsº on page230 for a comparison of POWER exits to JES2 exits.

10.3 JES2-POWER Functional Comparison

Charts follow which compare differences between POWER and JES2 in the following areas:

Input Services

Job Scheduling

Output Services

Interface to VSE/ICCF or TSO Remote Job Entry (RJE)

Chapter 10. POWER and JES2 211

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IBM OS/390 manual Tailoring JES2, 10.3 JES2-POWER Functional Comparison

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.