Mainframe Administrator

Mainframe Performance & Capacity Administrator - z/OS | Contract | Office Based

We are seeking an experienced Mainframe Performance & Capacity Administrator to support a large‑scale IBM z/OS enterprise environment. This is a high-impact contract role focused on performance tuning, capacity planning, and cost optimisation across mission‑critical mainframe systems.

You will lead performance and capacity initiatives across complex z/OS, SYSPLEX and PR/SM environments, ensuring optimal utilisation of CPU, memory, DASD and WLM‑managed workloads. This role requires deep expertise in RMF, SMF, MXG, MICS, SAS and TMON, along with strong knowledge of MIPS, MSU, 4

HRA and soft capping models.

• Analyse RMF and SMF records to diagnose performance issues
• Tune WLM service definitions and optimise workload placement
• Lead capacity forecasting and modelling across enterprise estates
• Support SCRT reporting and MSU cost management
• Optimise zIIP, GP processors and PR/SM configurations
• Provide 24/7 on‑call support for critical systems

• IBM z/OS performance and capacity management
• Strong experience with SMF, RMF, MXG, MICS, SAS or TMON
• Expertise in WLM tuning and SYSPLEX environments
• Proven capacity planning and performance optimisation experience
• Deep understanding of MIPS, MSU, 4
  
  HRA and soft capping

Experience with in large enterprise, banking, insurance or regulated environments is highly desirable.

This is a senior‑level contract opportunity offering strong visibility and ownership within a complex mainframe estate.

Apply now if you are a specialist in z/OS performance tuning and capacity management looking for your next contract challenge.