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, 4HRA and soft capping models.

Key Responsibilities

* 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

Essential Skills

* 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, 4HRA and soft capping

Experience within 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