Senior Mainframe Developer COBOL/DB2
Resume:
EZHAVENDHAN
Senior Mainframe Developer
*******.*******@*****.***
Mainframe Developer COBOL/ JCL/ VSAM/ CICS/NATURAL DB2/ IMSDB GOOGLE Cloud Certified Professional
Professional Summary:
With over 15+ years of dedicated experience as a Mainframe Developer, I have honed my skills in crafting robust solutions tailored to the needs of diverse industries.
Throughout my career, I have contributed my expertise to Banking, Financial Services, Healthcare, Telecom, and Transportation sectors, delivering high-quality software solutions that drive efficiency and innovation.
Have demonstrated proficiency across a comprehensive spectrum of mainframe technologies, including COBOL, JCL, DB2, VSAM, IMS DB/DC, CICS, REXX, Natural, ADABAS, EASYTRIEVE, and ASSEMBLER.
Experienced in leveraging Devin AI for AI-assisted analysis and reverse engineering of undocumented legacy COBOL programs, including repository exploration, program-flow analysis, dependency identification, business-logic understanding, code summarization, and technical documentation.
Extensively used GitHub Copilot for code analysis, development, code optimization, and accelerating delivery, helping improve development productivity and deliver high-quality solutions. Integrated GitHub Copilot with VS Code to support day-to-day development, code analysis, troubleshooting, and maintenance activities.
Possess hands-on experience with IBM iSeries/AS400 environments, including COBOL application development, legacy file-based application analysis, DB2 for i, and application modernization through File-to-DB2 migration initiatives.
Have adeptly utilized source code management tools such as ENDEVOR, SCLM, and CHANGEMAN.
Demonstrated proficiency in leveraging critical database tools such as PLATINUM, QMF, SPUFI, FILE-AID, and IBM ADMIN TOOL for seamless DB2 and IMS DB connectivity.
Possess extensive hands-on experience utilizing debugging tools such as INTERTEST, IBM DEBUGGER, and XPEDITOR to meticulously identify and rectify code bugs and defects.
Demonstrated adeptness in leveraging FILE-AID and File Manager to execute diverse file operations.
Possess advanced proficiency in utilizing essential utilities, including DFSORT, ICETOOL, IEBGENER, IDCAMS, IEBCOPY, and IEFBR14.
Have very good knowledge of job monitoring/scheduler tools such as CA7, CONTROL-M, and OPC/E.
Possess extensive knowledge of the processes involved in the Payments and Cards industry.
Proficient in navigating various communication protocols, including MQ, FTP, and NDM file transfer to ensure seamless data transmission and secure file sharing within organizational frameworks.
Familiar with change management practices, Agile, and Scrum methodologies, ensuring smooth integration of changes into existing systems.
Having good knowledge of working with application databases including Oracle and DB2, with expertise in table creation, updates, query optimization, and data loading/unloading processes.
Proficient in integrating mainframe systems with modern tools and platforms such as ServiceNow and Jira.
Demonstrated ability to effectively coordinate with Business Analysts (BAs), Development Leads, offshore teams, and Line of Business (LOB) stakeholders on a regular basis.
My experience spans the full software development lifecycle, from requirements gathering and analysis to application design, coding, testing, deployment, and ongoing support.
Provided technical leadership and guidance to junior developers, assisting them with problem-solving and skill development.
Consistently receive positive feedback from stakeholders and clients for delivering solutions that exceed expectations in terms of functionality, reliability, and user experience.
Technical Skills:
Programming Languages
COBOL, CICS, MVS/JCL, REXX, IMS, IDMS, ASSEMBLER
DBMS
DB2, VSAM, IMS DB, SQL, Stored Procedure, DB2 Utilities, Teradata.
Tools
TSO/E, ISPF, QMF, ENDEVOR, MQ, SCLM, ControlM, TWS, FILEMASTER, File-AID, Queryman, zOS Connect.
IBM DEBUGGER, XPEDITOR, INTERTEST, CA7, OPC/E.
Configuration Management Tools/others
SCLM, ENDEVOR, ZOS, I-SERIES
BIGQUERY, DATAFLOW, DATAPROC, GITHUB, JENKINS
Client: Fiserv Aug 2025 to till date
Role: Senior Cobol Developer
Roles and responsibilities:
Led analysis of existing COBOL applications, files, copybooks, dependencies, and execution flows to support the File-to-DB2 migration, performing detailed impact analysis across affected application components.
Performed pre and post-execution dependency analysis for online and batch programs, identifying required files, libraries, programs, jobs, data conditions, and downstream processes and assessing impacts of application changes.
Conducted environment and application readiness analysis across development, test, QA, and production environments, evaluating configuration, dependencies, data availability, and migration requirements.
Leveraged Devin AI to analyse GitHub repositories and reverse-engineer undocumented COBOL applications, identifying program flows, business rules, file/database access, dependencies, and downstream impacts.
Utilized Devin AI for AI-assisted code exploration, program summarization, business-rule analysis, dependency discovery, reusable logic identification, and technical documentation, with developer-led review and validation of generated findings.
Leveraged GitHub Copilot with VS Code for AI-assisted COBOL code analysis, development, troubleshooting, optimization, and documentation, improving development productivity and delivery efficiency.
Enhanced and modernized COBOL applications for File-to-DB2 migration, converting legacy file-based processing to DB2-integrated application logic while preserving established banking business rules and processing requirements.
Collaborated with Business Analysts, business users, DB2, QA, and downstream teams to analyse requirements, define technical solutions, resolve complex application issues, and ensure alignment across dependent systems.
Designed and developed batch programs and data validation processes supporting migration, reconciliation, data integrity, and verification between legacy files and target DB2 structures.
Utilized VS Code and GitHub for source-code analysis, COBOL development, version control, branching, pull requests, code reviews, and cross-team development collaboration.
Led application testing and defect resolution across unit, integration, system, and regression testing, troubleshooting COBOL, file, and DB2 issues and identifying opportunities for performance and maintainability improvements.
Authored and maintained technical documentation covering program logic, execution dependencies, file-to-DB2 mappings, data flows, business rules, environment requirements, and migration impacts; conducted technical walkthroughs and knowledge-transfer sessions with development and business teams.
Technology & Tools Used: COBOL, DEVIN AI, Github Copilot, iSeries/AS400, DB2 for i, SQL, VS Code, GitHub, STRSQL.
Client: California Department of Motor Vehicles Jun 2024 to Aug 2025
Role: Mainframe Technical Lead
Roles and responsibilities:
Acted as Subject Matter Expert (SME) for complex legacy DB2 data sources, including multi-layered table structure.
Collaborated with business users to understand data requirements, extraction criteria, and downstream consumption needs.
Used JCL, COBOL, and DFSORT utilities to perform large-scale data extraction, filtering, and formatting.
Reviewed and reverse-engineered Assembler and CICS modules to decode complex record structures and DB2 access logic.
Interpreted functional requirements and converted them into technical logic for data extraction using COBOL and JCL.
Designed and developed mainframe batch jobs to extract high-volume, nested DB2 data with complex record patterns.
Decomposed and restructured multi-segment DB2 records into normalized formats for external processing.
Led discovery sessions to identify undocumented business logic embedded in source systems.
Partnered with data engineer to transform mainframe output using Python scripts aligned to project expectations.
Supported data profiling efforts by highlighting anomalies, outliers, and inconsistent data formats.
Participated in resolving data quality issues by tracing root causes in source systems and recommending fixes.
Validated data integrity between DB2 source records and transformed outputs in staging environments.
Authored comprehensive technical documentation including data flow diagrams, record layouts, and transformation mappings.
Facilitated knowledge sharing and walkthroughs with business analysts, developers, and engineering teams.
Ensured consistency and completeness in all technical deliverables, including documentation, JCL streams, and extraction logic.
Acted as liaison between legacy mainframe teams and modern data platform teams to ensure seamless integration.
Technology & Tools Used: COBOL, CICS, JCL, DB2, Assembler, Endevor, REXX, VSAM, File Aid.
Client: Verizon Wireless Jul 2021 to May 2024
Role: Senior Mainframe Developer
Roles and responsibilities:
Developed and maintained mission-critical applications using COBOL and CICS, ensuring high performance and reliability.
Implemented IMS DB/DC databases and transactions for efficient data processing and retrieval.
Utilized ENDEVOR for version control and source code management, facilitating collaboration among team members.
Lead the modernization initiative of legacy mainframe systems by migrating monolithic applications to microservices architecture.
Optimized SQL queries and database access patterns to significantly improve the performance of critical mainframe applications.
Implemented caching mechanisms and data replication strategies to reduce response times and enhance user experience.
Conducted thorough performance profiling and tuning using tools like BMC Performance Analyzer to identify and address bottlenecks.
Developing and maintaining application programs through coding efforts.
Conducting peer reviews of code and addressing review comments in defect prevention meetings.
Writing test cases, conducting testing, and analysing and debugging code.
Deploying code into production environments during implementation phases.
Providing warranty support for deliverables and assisting with production issues during support phases.
Proposing novel ideas and enhancements to optimize the efficiency of current processes.
Automating tasks and procedures while employing performance tuning techniques to streamline operations and reduce manual workload.
Guiding new team members in programming languages and offering technical assistance and encouragement to the entire team.
Technology & Tools Used: COBOL, CICS, IMS DB/DC, ENDEVOR, SPUFI, Xpeditor, JCL, REXX, DB2, VSAM, IDMS, File Aid, QMF, CA7.
Client: Deutsche Bank Aug 2016 to Jul 2021
Role: Mainframe Developer
Roles and Responsibilities:
Engaged closely with business users to discern and fulfill application requirements effectively.
Proficiently developed projects utilizing COBOL, CICS, JCL, VSAM, DB2, ASSEMBLER and IMSDB technologies.
Built the required coding with COBOL, CICS, XML parser programs.
Contributed to enhancing system efficiency through performance tuning of DB2 modules and JCL.
Facilitated seamless coordination with upstream and downstream teams to ensure accurate data validation.
Strong understanding of mainframe databases like DB2 and IMS DB.
Experience with mainframe development tools such as IBM z/OS, CICS, and VSAM.
Familiarity with debugging tools like IBM Debug Tool and Xpeditor.
Collaborated with QA teams to conduct thorough testing procedures, ensuring the reliability and accuracy of developed applications.
Designed and implemented error handling mechanisms within COBOL programs to improve system stability and minimize downtime.
Actively participated in code reviews and provided constructive feedback to team members, fostering a culture of continuous improvement.
Assisted in the migration of legacy systems to modern platforms, leveraging knowledge of both mainframe and distributed technologies.
Developed and maintained comprehensive documentation for developed applications, aiding in knowledge transfer and onboarding of new team members.
Technology & Tools Used: COBOL, ASSEMBLER, CICS, IMS DB/DC, ENDEVOR, SPUFI, IDMS, Xpeditor, JCL, REXX, DB2, VSAM, File master, QMF.
Client: Blue Cross Blue Shield of Minnesota Dec 2013 to Aug 2016
Role: Mainframe Developer
Roles and Responsibilities:
Skilfully executed projects by employing COBOL, CICS, JCL, VSAM, DB2 and IMSDB technologies.
Played a key role in optimizing system performance through the fine-tuning of DB2 modules and JCL.
Facilitated smooth collaboration with upstream and downstream teams to ensure precise data validation.
Well-acquainted with debugging tools like IBM Debug Tool and Expeditor.
Resolved incidents related to Job Abends and Data Issues reported by Business Application Users, ensuring minimal disruption to business operations.
Analysed code and data to address issues and inquiries from Business Stakeholders, handling low-priority incidents and Service catalogue tasks efficiently.
Designed and developed a Pricing System featuring a user-friendly screen interface for maintaining pricing code details against provider network numbers.
Have extensively performed code changes for the business changes in message formats.
Managed the maintenance of plan code numbers for Blue-Cross and Blue-Shield plans across multiple states, facilitating the processing of provider claims via the Inter-plan Teleprocessing System.
Technology & Tools Used: COBOL, CICS, IMS DB/DC, ENDEVOR, SPUFI, Xpeditor, JCL, REXX, DB2, VSAM, File Manager, QMF.
Client: Medco Health Solutions Oct 2010 – Dec 2013
Role: Mainframe Natural ADABAS Developer
Role and Responsibilities
Designed, developed, and maintained Mainframe Natural ADABAS applications to meet business requirements.
Developed detailed technical specifications and design documents based on business requirements.
Wrote, debugged, and tested Natural programs and ADABAS database components.
Optimized application performance and enhanced system reliability through code refactoring and performance tuning.
Provided production support and resolved issues in a timely manner to minimize downtime.
Participated in code reviews and provided constructive feedback to team members.
Implemented enhancements and upgrades to existing Mainframe Natural ADABAS applications, incorporating new features and functionalities.
Created and maintained comprehensive documentation including user manuals, system diagrams, and technical guides to facilitate knowledge transfer and support future development efforts.
Actively participated in Agile or Scrum ceremonies such as sprint planning, daily stand-ups, and retrospectives to foster collaboration and continuous improvement.
Stayed current with emerging technologies and industry trends, attending training sessions and conferences to expand knowledge and skills in Mainframe development and related technologies.
Technology & Tools Used: Natural, ADABAS, ENDEVOR, SPUFI, INTERTEST, JCL, REXX, File Aid.
Certificates:
Banking and Financial Services certification (L0 Level)
IBM certified Database associate in DB2-730 Fundamentals.
Google Certified Professional Data Engineer & Cloud Digital Leader.
EDUCATIONAL QUALIFICATION:
Master of Computer Applications, Pondicherry University, Pondicherry, 2010.
Bachelor of Science, Madras University, Tamil Nadu, 2007.
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