We are seeking a highly experienced Mainframe Assembler Practitioner with deep expertise in IBM z/OS Assembler (HLASM) and strong hands on capability to rewrite assembler programs into COBOL, validate functional equivalence, fix defects identified during testing, and optimize performance. The role also requires the ability to analyze and document complex assembler logic, translating low level technical constructs into clear functional and business oriented documentation.

Responsibilities

- Assembler Code Analysis Understanding

- Analyze complex IBM z/OS Assembler (HLASM) programs, macros, and control blocks to fully understand:

- Business logic and functional flows

- Data structures, register usage, and storage management

- Control flow patterns (branching, looping, error handling)

- Perform call chain and dependency analysis, including interactions with:

- COBOL programs

- CICS/Batch environments

- Databases (DB2, VSAM, IAM, Datacom)

- Utility and system services

- Identify and document implicit business rules embedded in assembler logic, including edge cases and exception handling.

- Assembler to COBOL Rewrite

- Rewrite assembler programs into functionally equivalent COBOL code, ensuring:

- Logical equivalence with original assembler behavior

- Compliance with enterprise COBOL standards

- Maintainable, readable, and modular COBOL structures

- Translate low level assembler constructs (register operations, bit manipulation, packed/zoned decimal handling) into appropriate COBOL constructs.

- Handle conversion of:

- Batch programs

- CICS online programs

- Utility and interface modules

- Work closely with automated or semi automated rewrite tooling where applicable, validating and refining generated code.

- Testing Validation





- Design and execute unit and integration test cases to validate COBOL code against original assembler behavior.

- Support mainframe comparison testing where original assembler acts as the system of record for validation, a common pattern in complex rewrite programs.

- Analyze test failures by:

- Comparing assembler logic, extracted business rules, and rewritten COBOL code

- Identifying functional mismatches, data handling issues, and boundary condition errors

- Iteratively fix defects in rewritten COBOL code and re test until functional equivalence is proven.

- Performance Optimization

- Analyze performance critical assembler code paths, including:

- CPU intensive loops

- I/O heavy operations

- Storage and memory utilization patterns

- Optimize assembler or rewritten COBOL code by:

- Reducing instruction count or inefficient branching

- Improving data access patterns

- Minimizing unnecessary I/O or storage operations

- Ensure that rewritten COBOL meets or exceeds original assembler performance benchmarks where required.

- Functional Technical Documentation

- Produce clear, structured documentation describing:

- Program purpose and high level business functionality

- Detailed logic flow and decision points

- Input/output structures and file/database interactions

- Translate assembler level technical details into language consumable by functional analysts, testers, and downstream developers.

- Document assumptions, limitations, and known edge cases uncovered during analysis and rewrite.





- Collaboration Governance

- Collaborate with:

- Architects, testers, and modernization leads

- Automation, tooling, and QA teams

- Participate in design reviews, code walkthroughs, and defect triage sessions.

- Adhere to enterprise governance standards for code quality, documentation, and testing artifacts.

Required Skills Experience

- Core Technical Skills

- 10+ years of hands on experience with IBM z/OS Assembler (HLASM).

- Strong expertise in COBOL (Enterprise COBOL) on z/OS.

- Deep understanding of:

- z/OS execution model

- Register usage and storage management

- Assembler macros and copybooks

- Experience with Batch and CICS environments.

- Solid knowledge of mainframe data technologies:

- VSAM, IAM

- DB2 and/or Datacom

- Rewrite Testing Expertise

- Proven experience in assembler to COBOL rewrites, preferably in large modernization programs.

- Robust debugging skills across assembler and COBOL.

- Experience designing and executing test strategies for legacy rewrites.

- Ability to reason about behavioral equivalence, not just syntactic conversion.

- Performance Quality

- Demonstrated ability to analyze and optimize performance critical mainframe code.

- Strong attention to detail and root cause analysis skills.

- Documentation Communication

- Ability to document complex low level logic in a clear and structured manner.

- Strong written and verbal communication skills.

- Comfortable explaining assembler logic to non assembler practitioners.

Disclaimer: This job posting and Location has been aggregated from external source. Role details, content, and availability are subject to change. Applicants are advised to confirm the latest information directly on the company website before applying.

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