Mainframe Integration Engineer, London, £neg

Mainframe Integration Engineer

We're supporting a major digital banking programme and looking for an experienced Mainframe Integration Engineer to help modernise mission-critical payment systems. This role sits across Legacy and modern stacks - linking CICS/Db2 on z/OS with Java/Spring APIs on AWS.

This will be Hybrid London (two days a week, but flexible), Inside Ir35 and a long term contract.

What you'll work on:-
Core Mainframe Engineering

• Engineering CICS transactions, Db2 stored procedures and batch flows (JCL/REXX)
• Working with MQ, VSAM, GDGs, copybooks and Mainframe data structures

IBM DataPower & API Mediation

• Configuring MPGW & WSP services
• Implementing AAA, OAuth2/JWT, MTLS, WS-Security policies
• Building transformations (XSLT/GatewayScript)

Mainframe and Cloud Integration

• Integrating with AWS API Gateway/TYK
• Building Java/Spring Boot microservices aligned to payment services

Essential experience:

• 12+ years with z/OS, CICS and Db2
• Strong JCL, REXX, VSAM, GDG, MQ
• Knowledge of Cobol/Assembler (reading/debugging)
• Experience with CICS channels, containers, pipelines and web services
• Db2 performance tuning (BIND, EXPLAIN, RUNSTATS)

Nice to have:

• Java 17+, Spring Boot
• AWS (Aurora PostgreSQL, API Gateway)
• ISO 20022, Faster Payments, BACS, CHAPS