Mainframe Modernization: Transforming IBM CICS COBOL to Java for the Cloud

Modernizing IBM Z/OS COBOL applications to Java or C# brings major benefits for performance, scalability, and cost. Running these systems on cloud platforms such as AWS or Azure reduces infrastructure costs and improves flexibility.

As COBOL and CICS skills become harder to find, converting to modern Java or C# systems helps organizations lower risk, improve security, and take advantage of cloud reliability and updates.

By moving to Java, enterprises gain access to a larger talent pool and can use modern tools, APIs, and frameworks. This shift helps them stay agile and competitive in a fast-changing digital world.

Case Study: ING Bank migrates from IBM Mainframe COBOL to Java Cloud

SoftwareMining Approach to CICS Modernization

SoftwareMining modernizes IBM Z/OS COBOL applications to Java with a focus on maintainability, performance, and long-term scalability. Our automated process converts business logic into clean, object-oriented Java while preserving behavior and reliability.

VSAM and KSDS Migration: Converts file access to Object-Relational methods. See VSAM to Java Conversion for details.
Integration with Modern Platforms: Supports Tomcat, WebLogic, and IIS (for C#). Replaces KSDS files with SQL databases.
Readable User Interfaces: Generates JSP or XHTML from BMS screen definitions for easier maintenance.
Web Services: Exposes core logic through REST APIs for system-to-system communication.
CICS Compatibility: Includes Java libraries that support RACF, Temporary Storage Queues, program scheduling, and date-time utilities.

Key Components of a CICS COBOL to Java Migration

1. From Pseudo-Conversational to Session-Based Design

Legacy CICS programs release memory between user interactions. Modernized versions use session-based Java or C# services that keep the same logic while running efficiently on scalable, cloud-friendly frameworks. This makes the system faster, easier to deploy, and cloud-ready.

2. Converting BMS Screens to HTML

BMS defines the screens in IBM CICS applications. SoftwareMining automatically converts these to JSP, ASP, or XML, which are rendered as HTML at runtime. This preserves screen behavior while improving readability and maintainability.

Maintains original screen logic to reduce testing effort.
Produces simple, readable markup for future developers.
Allows easier UI upgrades and enhancements.

3. Indexed File Handling (EXEC CICS READ/WRITE/REWRITE)

CICS file commands such as READ, WRITE, and REWRITE are mapped to Java Data Access Objects (DAOs). These DAOs can connect to the original VSAM datasets or to SQL databases, allowing a gradual, low-risk migration path.

4. Security and RACF Integration

IBM mainframes use RACF for user access control. The SoftwareMining framework includes a built-in security manager and optional LDAP integration to match enterprise security policies and compliance needs.

5. IBM MQ Integration

Many COBOL applications use IBM MQ for messaging. SoftwareMining converts MQ API calls to neutral Java interfaces, preserving message flow while supporting modern frameworks such as JMS or ActiveMQ.

Example:

CALL 'MQGET' ...

becomes

MQManager.Get(...);

The MQManager class can be customized for other messaging platforms.

6. Additional CICS Libraries

SoftwareMining translates core CICS operations into Java or C# components that follow modern language patterns. This makes applications easier to maintain and removes dependency on legacy structures.

Supported CICS APIs in Java and C#

The SoftwareMining translation framework supports most of the commonly used CICS APIs. These APIs maintain the same functional behavior while using Java or C# syntax.

Error Handling

EXEC CICS HANDLE CONDITION Manage conditions.
EXEC CICS ABEND End a task abnormally.

Task Scheduling

EXEC CICS START Start a task at a specific time.
EXEC CICS RETRIEVE Retrieve data from expired START commands.

Flow Control

EXEC CICS LINK Call another program at a lower level.
EXEC CICS XCTL Transfer control to another program at the same level.
EXEC CICS RETURN Return control to the caller or framework.

Screen Handling

EXEC CICS SEND TEXT Send data to screen.
EXEC CICS SEND MAP Send mapped screen output.
EXEC CICS RECEIVE MAP Read input data into the program.

VSAM Access (via SQL/DAO)

EXEC CICS READ Read a record.
EXEC CICS WRITE Write a record.
EXEC CICS READNEXT / READPREV Navigate records sequentially.
EXEC CICS STARTBR / ENDBR Begin or end browsing records.

Temporary Storage Queues

EXEC CICS READQ TS / TD Read data from queues.
EXEC CICS WRITEQ TS / TD Write data to queues.
EXEC CICS DELETEQ TS / TD Delete queues.

Date and Time

EXEC CICS ASKTIME Get current system time.
EXEC CICS FORMATTIME Format date and time.

Miscellaneous

EXEC CICS ASSIGN Retrieve environment data.
EXEC CICS ROUTE Route output to printers.
EXEC CICS GET / DEFINE COUNTER Manage numeric counters.
EXEC CICS PUT / GET CONTAINER Store or retrieve data in containers.

Start Your CICS Modernization Journey

SoftwareMining provides automated tools and proven frameworks to convert COBOL to Java or C#, with full support for CICS, MQ, RACF, and other mainframe components. Our goal is to help enterprises modernize faster, reduce risk, and achieve full functional equivalence.

Learn more about our COBOL to Java/C# Conversion FAQ or contact our team for an enterprise briefing.