8.1.9 DL/I Multiple Partition Support

Conversion to IMS/ESA BMPs (Batch Message Processing programs) running under DBCTL should be considered as an alternative to CICS/OS Shared Data Base or IMS/ESA Data Sharing support.

8.1.10 Additional Information

A recently announced Redbook, Interoperability between VSE DL/I and OS/390 IMS DBCTL, SG24-5249, can provide additional conversion information.

8.2 SQL/DS to DB2 for OS/390 Migration Consideration

Note: Although the formal name of the SQL/DS product has changed to DB2 for VSE, this document will use the name SQL/DS. This document will also use the term ′DB2′ to mean the full product name - ′DB2 for OS/390′.

8.2.1 Descriptions of Users

The differences and thus the migration considerations between SQL/DS and DB2 take on meaning only as they pertain to, or are perceived by, the users of the products. In order to discuss this, we need to define who these users are. The type of users we want to address are:

∙

∙

∙

∙

∙

End Users

Application Developers

Data Base Administrators (DBAs)

System Administrators

Security Administrators

It is important to point out at this time that the following is not meant to provide an exhaustive list of differences between the two products. Instead, it is intended to point out the most likely areas of difference you will encounter to give a feeling for how significant or insignificant these differences may be. An exhaustive treatment and explanation of the differences in the VSE and OS/390 platforms is given in the IBM SQL Reference, SC26-8416. This can be ordered through standard IBM document ordering procedures.

As we will see later, the area of most concern is with the language of both products - the Structured Query Language or SQL. SQL has the three following

′flavors′:

1.Data Manipulation Language (DML) that is used by End Users and Applications Developers

2.Data Definition Language (DDL) that is used by DBAs and Systems Administrators

3.Data Control Language (DCL) that is used by Security Administrators.

8.2.1.1 End Users

From the standpoint of end users, for DML, there are very few differences between SQL in the two products. DML is what most end users use - the issuance of SELECT, UPDATE, INSERT and DELETE statements to do work against a database. End users rarely have a need to know or use DDL or DCL. As we will see later, the latter two SQL ′flavors′ are used mostly by DBAs,

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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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