Senior z/OS Systems Programmer

About Us: Ensono is a hybrid IT services provider that sees a world in transformation. We understand the world of business has become more complex, layered, and interdependent because we’re enabling the IT infrastructure for that transformation. Our clients are some of the most innovative and forward-thinking companies in the world and we help keep their businesses thriving. With nearly 50 years of experience, we optimize and modernize IT infrastructure by amplifying the power of mainframes and mid-range servers with the agility of cloud. Check us out at www.ensono.com. Job Role: As a Senior z/OS Base System Engineer, you will act as a key technical leader in maintaining and advancing our core mainframe operating system environment. We’re looking for an experienced z/OS Systems Software Engineer to: design, develop, and improve the core digital platform services we provide on z/OS. You will apply a broad range of software engineering practices , from analyzing system needs and developing new features to automated testing and deployment. You’ll ensure the quality, security, reliability, and compliance of our operating system solutions by implementing both functional and non-functional requirements. You’ll help build observability into our systems, monitor production health, resolve incidents, and perform root-cause analysis to improve stability. In addition, you will monitor and optimize Parallel Sysplex and Coupling Facility configurations , ensuring high availability across mainframe clusters. As a senior engineer, you will make critical technical decisions and articulate your solution designs and proposals to stakeholders and technical leadership, serving as a trusted advisor on mainframe systems architecture. You will also share knowledge and expertise with colleagues, mentor junior engineers, and contribute to our engineering culture via code reviews, technical presentations, and participation in internal communities. Your team: In our agile operating model, crews are aligned to larger products and services that fulfill business needs through multiple autonomous pods. You’ll be working in the Mainframe Platform Core Services team , a global crew responsible for mainframe infrastructure services and innovation. You will collaborate closely with other specialized mainframe engineering teams (e.g., DB2 Engineering and Online Systems Engineering for CICS/MQ) to deliver end-to-end reliable solutions. This role involves frequent interaction with operational teams across geographies (such as Switzerland, USA) to ensure alignment of system enhancements and operations. As a senior member, you’ll often interface with lead engineering boards and stakeholders to align mainframe platform improvements with business goals. Mandatory Skills You have 10+ years’ experience in z/OS systems programming or a similar senior engineering role. Your qualifications include: Deep knowledge of z/OS internals – Expert skills in z/OS operating system architecture, design, and implementation , with mastery of core z/OS components and subsystems. Parallel Sysplex & Coupling Facility mastery – Comprehensive experience in Geographically Dispersed Parallel Sysplex (GDPS) operations and Coupling Facility management to ensure high availability and minimal outages. SMP/E and system installation – Hands-on expertise with SMP/E packaging, installation, and maintenance of z/OS software and operating system; capable of planning and executing complex system upgrades and ensuring OS currency (experience up to z/OS 3.1 preferred). Programming & Scripting – Proficiency in REXX , TSO/ISPF, JCL, and other system programming languages; familiarity with Assembler coding is a plus. Performance & Tools – Strong analytical skills and thorough knowledge of z/OS performance tuning and system utilities; experience with IBM and non-IBM system management tools, monitoring, and problem determination utilities. Problem Management & Support – Proven experience providing Level 3 sup…