Senior Mainframe Assembler Developer (HLASM / z/OS)

Senior Mainframe Assembler Developer (HLASM / z/OS)

Project Details

• Location: Central & Eastern Europe
• Workload: Full-time
• Duration: Long-term

• Rate: $23–25/hour (B2B)

   

We are looking for an experienced Senior Mainframe Assembler Developer to join a long-term project focused on developing, optimizing, and maintaining low-level applications within an IBM mainframe environment.

The role requires deep expertise in HLASM, IBM z/OS, system-level debugging, and performance optimization.

Responsibilities

• Develop, maintain, and optimize Mainframe Assembler (HLASM) code.
• Analyze complex system requirements and implement reliable low-level solutions.
• Debug production issues, analyze system dumps, and resolve critical incidents.
• Optimize application performance, memory usage, and I/O operations.
• Integrate Assembler modules with COBOL, PL/I, and Java applications.
• Work with IBM mainframe technologies, including z/OS, CICS, IMS, and DB2.
• Troubleshoot system-level issues using IPCS, SYSUDUMP, and specialized debugging tools.
• Collaborate with technical teams and stakeholders to ensure system stability.
• Participate in code reviews, technical documentation, mentoring, and knowledge transfer.

Requirements

• 7–10+ years of professional Assembler development experience, including at least 5 years working with mainframe systems.
• Strong hands-on expertise in HLASM (High Level Assembler).
• Deep understanding of IBM mainframe architecture, instruction sets, and macros.
• Strong experience with IBM z/OS, MVS, CICS, IMS, and DB2.
• Knowledge of VSAM, GDGs, and JCL.
• Understanding of memory management, I/O operations, and interrupt handling.
• Experience with low-level debugging and dump analysis using IPCS and SYSUDUMP.
• Familiarity with IBM Debug Tool, Abend-AID, OMEGAMON, or Fault Analyzer.
• Experience integrating Assembler modules with COBOL, PL/I, or Java.
• Understanding of APIs, MQ messaging, and middleware.
• Strong analytical, troubleshooting, and problem-solving skills.
• Good communication skills and experience supporting knowledge transfer.

Nice to Have

• IBM Certified System Programmer certification.
• IBM z/OS Mastery certifications.
• Experience mentoring other mainframe developers.

If you have extensive hands-on HLASM expertise and enjoy solving complex system-level challenges within IBM mainframe environments, we'd be happy to hear from you!