2.7 Scope of Work and Challenges

When converting VSE applications to OS/390 several tasks have to be performed. The following sections describe the most important work items involved and some of the challenges which can be encountered during the execution of these tasks:

∙

∙

∙

∙

∙

∙

Application inventory

Program conversion

JCL conversion

File migration

Automated operations setup

Project management

2.7.1 Application Inventory

For a VSE to OS/390 conversion, the application inventory is nearly always underestimated in both duration and labor.

The main application inventory activities include:

∙

∙

Determining what VSE applications must be converted to OS/390

Retrieving and collecting the current production version of each application item

∙Transferring those items to the conversion input libraries on the OS/390 system

∙Verifying that the transferred inventory has no missing or unused items

One of the challenges when establishing an application inventory for a VSE to OS/390 conversion is that the application programs must be precisely matched with the JCL streams (for batch applications) and CICS tables (for online applications) to be converted. This is because of the considerable blending of application code and VSE JCL streams (see JCL conversion below). Building these ²work units² adds work at project start, but it becomes a significant deliverable at project completion, when the new OS/390 application inventory used in production is perfectly defined and centrally stored, with no missing or unused items.

Application inventory tools are used to identify missing and unused items. Missing items must be retrieved or recoded (if possible from a previous version), regression tested under VSE, and used in production under VSE before being converted to OS/390. Unused items must be eliminated or the item using them must be added to the application inventory. The identification, collection and transfer of the application inventory are repeated until the verification identifies no missing or unused items.

The application inventory often leads to a re-organization of the VSE storage. Unique centralized libraries are defined, allocated and used to store the current production version of any application item. Obsolete or duplicate versions are moved to non-production archive libraries.

The application inventory may last two to four months and represent 10 to 15% of the total application conversion effort.

32VSE to OS/390 Migration Workbook

Page 55 Page 57
Page 56
Image 56
IBM OS/390 manual Scope of Work and Challenges, Application Inventory
Page 55 Page 57

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.
Top Page Image Contents