Mainframe Developer

Job Title: Senior Mainframe Developer

Location: Atlanta, GA (Hybrid)

Duration: 12+ Months

Contract: W2 Only

About the Role

We are seeking a highly experienced and proficient Senior Mainframe/COBOL Developer to maintain, enhance, and modernize our mission-critical legacy systems. You will be a technical expert responsible for ensuring the stability, performance, and reliability of core business applications that process millions of transactions daily. This role requires deep technical knowledge of the mainframe ecosystem, a meticulous attention to detail, and the ability to solve complex problems within a stable but evolving environment. You will also play a key role in knowledge transfer and guiding strategic decisions around system evolution and potential migration initiatives.

Key Responsibilities

• Analyze, design, code, test, debug, and maintain complex business applications using COBOL, with significant use of Assembler for performance-critical modules and system-level routines.
• Develop and maintain robust JCL (Job Control Language) for scheduling and executing batch jobs. Support and enhance CICS (or IMS DC) online transaction processing systems.
• Design and manage data access using VSAM (Key-Sequenced, Entry-Sequenced, Relative Record) and DB2, writing efficient SQL queries and optimizing database performance for mainframe environments.
• Utilize Endeavor (or a similar change management tool like Changeman) to manage code promotion, version control, and deployment processes across development, test, and production environments.
• Serve as the subject matter expert for mainframe technologies. Mentor junior developers and provide guidance on best practices, system debugging, and performance tuning.
• Provide high-level (L3) production support, performing root cause analysis for complex issues, implementing fixes, and ensuring 24/7 system availability as part of an on-call rotation.
• Collaborate with architecture teams on initiatives to modernize legacy systems, including designing and building APIs (using z/OS Connect, CICS Web Services) to facilitate integration with distributed systems (Java, .NET, Cloud).
• Create and maintain detailed technical specifications, run books, and system documentation to ensure knowledge preservation and operational continuity.

Required Qualifications & Skills

• 10+ years of hands-on experience in designing, developing, and supporting large-scale mainframe applications in an enterprise environment.
• Expert-level proficiency (COBOL/370, COBOL II, or Enterprise COBOL).
• Strong working knowledge and experience with HLASM (High-Level Assembler) for system-level programming and optimization.
• Expert in writing, debugging, and optimizing complex JCL procedures and utilities (SORT, IDCAMS, IEBGENER).
• In-depth experience with VSAM file design, access methods (KSDS, ESDS, RRDS), and performance tuning.
• Proficient in DB2 SQL (embedded and dynamic), SPUFI, DCLGEN, and understanding of DB2 optimization (EXPLAIN, indexes).
• Proficient with Endeavor or a comparable mainframe software change and configuration management (SCCM) tool.
• Experience with TSO/ISPF, SDSF, and File-Aid or similar data browsing/editing tools.
• Familiarity with CICS (or IMS DC) command-level programming and debugging (CEMT, CEDF).
• Excellent analytical, problem-solving, and debugging skills for complex system-level issues.
• Strong understanding of the Software Development Life Cycle (SDLC) in a mainframe context.
• Ability to work independently with minimal supervision and lead technical efforts.
• Highly organized with the ability to manage multiple priorities in a production-critical environment.

Preferred Qualifications

• Experience with CA Gen or ADABAS/Natural.
• Knowledge of mainframe modernization strategies and tools (Micro Focus, Heirloom, AWS Mainframe Modernization).
• Experience with MQ Series for mainframe-to-mainframe or mainframe-to-distributed communication.
• Familiarity with REXX or CLIST for automation.
• Exposure to DevOps concepts for the mainframe (automated testing, CI/CD pipelines).
• Understanding of z/OS UNIX System Services (USS).