functional descriptions of batch applications (standards and system independent).

EZ-PCL (Easy PCL)

A PC/MS-Windows based graphic user interface (GUI) to the PDB, which enables definition or modification of batch applications in their flowchart representation.

PREP (Preparation)

An interactive system of preparation, submission, backout, and restart of OS/390 jobs.

SWITCH (Switchover)

Transfers VSE files to OS/390 and DFSMS using VSE and

OS/390 file information stored in the PDB.

ENV (Environment)

A set of subroutines supplied in source format that may be required to simulate VSE functions without an OS/390 equivalent: ISAM, COMREG, UPSI, and so on.

Some of the CORTEX MS/ENV simulation subroutines may be used for execution of the converted applications. Otherwise, no other CORTEX MS components are required for OS/390 operations.

Figure 57 illustrates the automated conversion process that can be developed, using the CORTEX Migration System, to convert VSE applications to OS/390.

Figure 57. Automated Conversion Process

The discussions that follow address the functions provided by mass migration tools. The tool and process being referred to is the CORTEX MS aid developed by SISRO and licensed to IBM as the MVS-MS (Migration System).

The key functions provided by the mass conversion tool are:

Chapter 32. Conversion Process 491

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IBM OS/390 manual EZ-PCL Easy PCL, Prep Preparation, Switch Switchover, ENV Environment
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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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