Senior z/OS Systems Programmer - Mainframe Modernisation

GL Global; South Yorkshire; On-site; GBP 60,000 - 90,000; Full time

Job summary

GL Global is seeking an experienced IBM z/OS Mainframe professional to install, configure, and maintain z/OS system software and core subsystems, including JES, SMP/E, and TSO/ISPF.

You will lead upgrades, patching, and performance tuning, investigate complex issues, support platform migrations, and ensure security and compliance while collaborating with infrastructure and engineering teams in the UK.

Qualifications

• Extensive experience with IBM z/OS Mainframe environments.
• Strong knowledge of JES, SMP/E, and TSO/ISPF.
• Solid JCL experience and Mainframe automation scripting (REXX, CLIST).
• Proven ability to install, configure, upgrade, and maintain Mainframe system software and utilities.
• Experience with third‑party Mainframe tools (monitoring, storage, scheduling, performance management).
• Proactive approach to troubleshooting, platform reliability and continuous improvement.

Responsibilities

• Install, configure, and maintain z/OS system software and core Mainframe subsystems.
• Lead and support system upgrades, patching, maintenance, and performance optimisation.
• Investigate and resolve complex Mainframe system issues.
• Contribute to platform migrations, integrations, and wider modernisation projects.
• Ensure systems meet security, compliance, and regulatory requirements.
• Collaborate with infrastructure, engineering, and application teams to deliver robust, reliable solutions.

Skills

IBM z/OS

Mainframe subsystems

JCL

REXX/CLIST

Upgrades & maintenance

Security & compliance

Job description

The Role

• Install, configure, and maintain z/OS system software and core Mainframe subsystems.
• Lead and support system upgrades, patching, maintenance, and performance optimisation.
• Investigate and resolve complex Mainframe system issues.
• Contribute to platform migrations, integrations, and wider modernisation projects.
• Ensure systems meet security, compliance, and regulatory requirements.
• Collaborate with infrastructure, engineering, and application teams to deliver robust, reliable solutions.

Experience

• Extensive experience working with IBM z/OS Mainframe environments.
• Strong knowledge of core z/OS components and subsystems, including JES, SMP/E, and TSO/ISPF.
• Solid JCL experience, alongside Mainframe automation and scripting tools such as REXX, CLIST, or equivalent.
• Proven ability to install, configure, upgrade, and maintain Mainframe system software and utilities.
• Experience with third-party Mainframe tools and vendor products, including monitoring, storage, scheduling, or performance management solutions.
• A proactive approach to troubleshooting, platform reliability, and continuous improvement.