Mainframe Assembler Engineer - IBM z/OS / CICS / MQ

Mainframe Assembler Engineer - IBM z/OS / CICS / MQ

DURATION: 3 months initial contract

LOCATION: Edinburgh, Manchester, Leeds OR Halifax (2 days to local office)

WORKING HOURS: Monday to Friday, standard business hours plus participation in a 24/7 on-call rota

ONSITE REQUIREMENTS: Hybrid working with 2 days per week onsite at local office

ENGAGEMENT TYPE: Outside ir35

DAY RATE / HOURLY RATE: £600 per day

LEGAL RIGHT TO WORK: Candidates must have the legal right to work in the UK. Sponsorship is not available for this role.

ATRIUM GLOBAL SUMMARY

Atrium Global is supporting a major financial services client in the appointment of an experienced Mainframe Assembler Engineer to join a critical heritage engineering team supporting enterprise banking platforms and core transactional systems.

JOB OVERVIEW

We are seeking a highly experienced Mainframe Assembler Engineer with strong IBM z/OS expertise to support and enhance mission-critical banking systems. The role combines operational BAU support, incident resolution, technical change delivery and platform modernisation across a complex mainframe estate.

You will work across HLASM, CICS, IBM MQ and core z/OS technologies, supporting high-availability systems and contributing to transformation initiatives within a regulated enterprise environment.

This role includes participation in out-of-hours deployments and a 24/7 on-call support rota.

RESPONSIBILITIES

• Provide technical support for IBM High Level Assembler applications within a z/OS environment
• Support and troubleshoot CICS and IBM MQ integrated services
• Perform root cause analysis for incidents, abends and performance issues across production and non-production environments
• Develop, maintain and enhance Assembler code for planned releases and platform improvements
• Maintain and optimise JCL batch processing and transaction performance
• Support upgrades, migrations and infrastructure changes across the mainframe estate
• Collaborate with COBOL, DB2 and infrastructure teams to deliver integrated technical solutions
• Participate in release validation, deployment readiness and production support activities
• Ensure adherence to ITIL governance, operational standards and risk controls
• Contribute to technical documentation, design reviews and continuous improvement initiatives

REQUIREMENTS

• Proven experience supporting and developing IBM High Level Assembler (HLASM) on z/OS
• Strong hands-on knowledge of CICS, IBM MQ, JCL and VSAM
• Experience troubleshooting incidents and abends within enterprise mainframe environments
• Familiarity with tools such as Abend-Aid, IPCS, Omegamon or File-Aid
• Experience supporting both BAU operations and project delivery activities
• Understanding of COBOL and DB2 integration within mainframe platforms
• Knowledge of MQ security, TLS and operational governance controls
• Experience with automation or scripting tools such as REXX, Shell, Ansible or UrbanCode
• Strong analytical and problem-solving skills within high-availability environments
• Excellent communication and stakeholder collaboration skills

NICE TO HAVE

• Experience within financial services or highly regulated enterprise environments
• Exposure to modernisation or transformation programmes involving legacy systems
• Previous experience working within large-scale enterprise banking platforms