COBOL Mainframe Rehosting

Our COBOL Rehosting solution combines the industry’s best software platforms with proven application consolidation and data migration services to ensure your entire mainframe estate is deployed to the target environment in the languages and database models you need.

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Discussing the 2022 Mainframe Modernisation Report

60 minutes

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Why modernise?


Exorbitant costs

Mainframes running COBOL cost as much as 4,500 percent more to operate than equivalent Cloud counterparts. This figure is compounded by the rising licensing and maintenance fees for ancillary mainframe applications and databases. 

Limited flexibility

Companies are rapidly moving to modern environments and practices such as DevOps and the Cloud. However, the mainframe and its ancillary systems were not designed for modern IT agility, resulting in difficult integrations and limited flexibility.


Limited data accessibility

Legacy databases are difficult to integrate with systems on modern platforms. This is because of inherent inextensibility, incompatibility, and rigidity of the underlying hardware and software powering these legacy systems.

COBOL Rehosting


You can retain your COBOL as-is while taking advantage of the cost savings and infinite elasticity of the Cloud by rehosting your legacy estate with Advanced.

Rehosting, sometimes referred to as replatforming, is ideal for companies whose applications are still meeting their business needs, and who therefore wish to retain their COBOL development skills while moving away from non-relational databases and expensive mainframe infrastructure. With rehosting, COBOL is migrated onto modern, distributed platforms, either on-premises or in the Cloud, without change. Underlying legacy databases are migrated to relational models, configured to seamlessly interact with your applications via the rehosting platform.

Our COBOL Rehosting solution leverages three key service activities to account for the application source code, data and supporting operational infrastructure:

Application migration

During an assessment, our tools and modernisation experts catalogue the applications running in the mainframe estate, documenting dependencies and all application languages used. We also highlight dead and unused code that can be eliminated in the modernisation process to reduce the complexity and footprint of your source code. Core languages such as COBOL, PL/I, and JCL are retained and rehosted into the target environment of your choice. Leveraging our Automated Refactoring solutions, we consolidate other application languages into a single optimised language. For example, languages such as CA Telon or Natural which can be intermingled with COBOL on the mainframe can be consolidated to COBOL. This eliminates licensing fees and simplifies maintenance of your application on the rehosting platform.

Data migration

Our Automated Data Migration solution is leveraged to ensure existing legacy data files and databases are deployed in the desired model and optimised for the rehosting environment. Many data types such as VSAM, sequential, GDGs, IMS-DB, and certain relational databases can be retained in the rehosted environment. However, in some cases, a non-relational database is migrated to a relational model. For example, if your mainframe environment contains Adabas or IDMS databases, we would migrate them to SQL Server, Db2, Oracle, or PostgreSQL, depending on the rehosting platform, your preferences, and the nature of your applications.

Platform deployment

Deployment specifics depend on the rehosting platform and migrated estate, but this activity includes target environment sizing and architecture, identification of ancillary components (such as supporting third party solutions and utilities) that require replacement, deployment of the rehosting platform software, consolidated source code, utilities, and migrated databases, as well as testing and post-delivery support.

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Over 35 years of COBOL and mainframe modernisation experience

More than 500 successful modernisation projects completed

Over 2.5 billion lines of code refactored through automation

Intelligent modernisation, unparalleled experience


Additional resources to help you modernise



Don’t kick the COBOL can down the road

This whitepaper looks at the challenges of maintaining legacy applications, and the various COBOL modernisation options available.

Read whitepaper





Know the details, reduce the risk

This whitepaper details why a detailed assessment of legacy applications and databases is essential for risk mitigation prior to any modernisation effort.

Read whitepaper





2022 Mainframe Modernisation Report

Exploring the impact of the new era of digitalisation and change on the current state of legacy systems and organisations' modernisation plans.

Read report



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31 Aug 2022 by Rob Anderson, Vice President of Marketing and Product, Advanced

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10 Mar 2022 by Rob Anderson, Vice President of Marketing and Product, Advanced

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6 Apr 2021 by Rob Anderson, Vice President of Marketing and Product, Advanced

News & Opinions

// 08-06-2023

Webinar recap: Natural Adabas: Closing the skills gap and reducing risk

by Rob Anderson, Vice President of Marketing and Product for Application Modernization

Webinar recap: Natural Adabas: Closing the skills gap and reducing risk.