Mainframe Application Support and Modernization for a Global Technology Enterprise

Supporting 150+ business-critical IBM z/OS applications over two decades, enabling phased migration to SAP and legacy application decommissioning.

Background

A global technology enterprise relied on a large portfolio of IBM z/OS applications supporting core business processes, including customer records, order and contract management, pricing, billing, invoicing, inventory management, and financial operations.

For more than 20 years, IBA Group has provided mainframe application development and support services for the customer, maintaining over 150 business-critical applications through organizational changes, acquisitions, divestitures, and technology modernization initiatives.

As the customer gradually transitioned business processes to SAP, IBA Group’s role extended to supporting data migration, integration between the two environments, and legacy application decommissioning.

Client Challenge

The customer needed to maintain a complex mainframe application landscape while progressively replacing legacy functionality with SAP solutions.

Development and support of the mainframe application landscape were distributed across multiple teams operating in different time zones and following different processes. The customer needed to consolidate these activities while maintaining business continuity and gradually transitioning business functions to SAP.

The main challenges included:

Consolidating application development and support. Establishing a unified delivery model for more than 150 mainframe applications previously managed by multiple teams.
Maintaining business continuity. Keeping business-critical mainframe applications operational as individual functions transitioned to SAP.
Managing complex data transformations. Mapping different mainframe and SAP data models, including document splitting and consistent handling of identifiers and number ranges.
Supporting system coexistence. Integrating mainframe and SAP environments as business processes were gradually distributed between them.
Controlling legacy application retirement. Decommissioning applications only after the business confirmed their functionality was no longer required.

Solution

IBA Group combined long-term expertise in mainframe application development and support with migration, integration, and decommissioning services, covering the full lifecycle of business-critical applications.

Mainframe Application Development and Support

IBA Group assumed full responsibility for more than 150 IBM z/OS applications, providing mainframe application support services, including L2/L3 support, 24×7 coverage, incident analysis and resolution, business requirement implementation, regulatory changes, and Disaster Recovery support.

During the most active engagement period, the mainframe team included up to 50 specialists covering architecture, development, database administration, business analysis, testing, and delivery management.

The engagement also covered mainframe modernization initiatives, including API integration, DevOps, web enablement, and hybrid cloud migration activities.

Through this long-term involvement, IBA Group developed extensive knowledge of the customer’s mainframe applications, which became essential during the subsequent migration waves.

Mainframe Support for SAP Migration and Integration

As the customer introduced new SAP functionality, IBA Group’s mainframe specialists worked with SAP development teams to support the transition from legacy applications.

Rather than transferring entire applications or replicating their business logic, the mainframe team focused on providing the data, application knowledge, and interfaces required by the new SAP functionality.

IBA Group’s responsibilities included:

Analyzing specific business processes in existing mainframe applications to support migration requirements.
Supporting data extraction, mapping, and migration from legacy systems.
Addressing differences between mainframe and SAP data models, including one-to-many mappings, document splitting, and number-range consistency.
Developing and supporting interfaces between mainframe and SAP applications to maintain cross-system business processes.

In addition to its mainframe responsibilities, IBA Group provided SAP support and migration services, including data validation, transformation rules, production migration execution, and post-migration support.

Migration was performed in successive waves. SAP teams developed and tested new functionality, while mainframe teams supported the extraction of required mainframe data and integration with applications that remained operational.

Once the corresponding SAP functionality was activated, the legacy functionality could be deactivated, allowing the customer to progressively reduce its dependence on mainframe applications without interrupting ongoing business operations.

Legacy Mainframe Application Decommissioning

IBA Group supported the controlled retirement of mainframe applications following their replacement by SAP functionality.

Decommissioning decisions were made in coordination with the customer’s business stakeholders. Applications were not immediately removed after migration: they could remain inactive for a period, allowing reactivation if necessary or continued operation of dependent systems.

Once retirement was approved, IBA Group handled:

Application discovery and dependency assessment.
Coordination with business and technical stakeholders.
Suspension of application activities and data archiving.
Cleanup of mainframe resources, including IMS, CICS, DB2, MQ, TWS, RACF objects, and associated storage assets.

This phased approach allowed the customer to retire legacy applications as business requirements and system dependencies permitted.

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Mainframe Technology Environment

Platform: IBM z/OS

Programming languages: COBOL, PL/I, REXX, CLIST, Assembler, CSP, C, Java, JCL

Data management: Db2 for z/OS, IMS/DB, VSAM

Transaction processing and integration: CICS, IMS, IBM MQ, CICS Transaction Gateway, IMS Connect

Operations, security, and development: TWS/OPCE, RACF, TSO, ISPF, SDSF, SMP/E, SCLM, WLM, z/OS UNIX, IBM Developer for z/OS (IDz)

Results

The engagement enabled the customer to maintain business-critical mainframe operations while progressively transitioning its application landscape to SAP.

150+mainframe applicationssupported across global operations

20+yearsof mainframe development and support

90%+legacy applicationsreplaced and decommissioned

Business Continuity Throughout the Transformation

Mainframe and SAP environments operated in parallel throughout successive migration waves, allowing the customer to transition business functions while maintaining critical operations.