CICS development encompasses the practices, patterns, and methodologies used to build reliable, maintainable, and efficient CICS applications. Development in CICS involves understanding programming models, following coding standards, implementing proper testing strategies, and adapting to modern development practices. Understanding CICS development principles is essential for building applications that integrate seamlessly with the CICS environment while meeting business requirements and performance objectives.
CICS supports multiple programming models that define how programs interact and share control. The basic model involves a single program without special error handling. The LINK model uses subprograms called via LINK with the calling program resuming after the called program returns. The XCTL model permanently transfers control to another program. Understanding these models helps developers choose the appropriate approach for their application requirements.
Think of programming models like different ways to organize work. Basic model is like doing everything yourself. LINK is like asking someone to help with a task and then taking control back when they are done. XCTL is like handing over a project permanently to someone else.
Following consistent coding standards improves code quality, readability, and maintainability. Use meaningful variable names that reflect purpose. Avoid hardcoding values by using configuration or constants. Implement proper error handling for all CICS commands. Ensure proper resource cleanup in all execution paths.
Document code with clear comments explaining business logic and complex algorithms. Use consistent indentation and formatting. Group related code together and separate concerns with proper program structure. Follow company or project-specific standards consistently.
The CICS development lifecycle includes requirements gathering, system design, program coding, unit testing, integration testing, system testing, user acceptance testing, deployment, and ongoing maintenance. Each phase requires specific activities and deliverables.
Requirements gathering defines what the system must do. Design translates requirements into system architecture and program specifications. Coding implements the design in COBOL or other supported languages. Testing validates functionality, performance, and reliability. Deployment moves applications to production. Maintenance addresses issues and enhancements.
Comprehensive testing is critical for reliable CICS applications. Unit testing validates individual program modules. Integration testing verifies program interactions. System testing validates complete functionality. Performance testing ensures acceptable response times. User acceptance testing confirms business requirements are met.
Use CEDF for interactive debugging during development. Implement test data sets for consistent testing environments. Create automated test scripts where possible. Document test cases and results. Conduct regression testing when changes are made.
Modernize CICS development by implementing web services for interoperability. Use JSON for data exchange between systems. Adopt DevOps practices for continuous integration and deployment. Implement version control for all code and configurations. Use modern tools for development and testing.
Consider cloud integration for hybrid architectures. Implement REST APIs for modern interfaces. Use container technologies where appropriate. Adopt agile development methodologies. Embrace automation for builds, testing, and deployment.
Follow these practices for effective CICS development:
Think of CICS development like building with LEGO blocks:
Just like with LEGO, building CICS applications requires following instructions, using pieces correctly, and making sure everything works together!
Complete these exercises to reinforce CICS development skills:
Design a CICS application and determine which programming model is most appropriate. Document your reasoning and design the program structure.
Review existing CICS code and identify violations of coding standards. Refactor the code to follow best practices and document improvements.
Design comprehensive test cases for a CICS transaction, including normal processing, error conditions, and boundary cases. Document expected results.
Implement proper error handling in a CICS program. Include error checking for all CICS commands and appropriate user messaging.
Create a modernization plan for a legacy CICS application. Identify opportunities for web services, JSON integration, and modern interfaces.
1. What is the basic model in CICS programming?
2. What command transfers control permanently to another program?
3. What should be avoided in CICS programming?
4. What is CEDF used for?
5. What is JSON commonly used for in modern CICS?