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We are looking for an experienced and Senior Developer Java on Mainframe for Online Applications with specialized expertise in IBM z/OS mainframe environments, especially for online applications under CICS. This role goes beyond conventional Java development we need someone who understands how to engineer high-performance, low-latency Java applications that run natively on the z/OS platform and integrate seamlessly with legacy enterprise systems. This position requires deep knowledge of Java in the context of z/OS internals, particularly in the areas of Java Native Interface (JNI), database interaction (JDBC, SQLJ), and system-level online performance. You will work with both legacy and modern components to develop robust, high-throughput services that are critical to enterprise operations. Essential Skills Develop and optimize Java-based applications running natively on IBM z/OS in online mode under CICS Analyze and improve performance at the JVM level, focusing on memory usage, tuning, and CPU cycles on z/OS. Integrate Java applications with native z/OS components using JNI, C/C++, and LE (Language Environment) interfaces. Implement effective data access solutions using JDBC, SQLJ, and DB2 for z/OS best practices. Collaborate closely with z/OS systems programmers, DBAs, and COBOL/CICS developers to ensure reliable and performant interoperability. Review SMF records, RMF reports, and monitor WLM metrics to guide tuning and system integration. Develop and maintain shell scripts and support automation for Java workloads on z/OS. Drive initiatives to modernize legacy systems using Java and hybrid integration models. Minimum Requirements: Bachelors or masters degree in computer science, Software Engineering, or a related field. 8+ years of professional Java development experience, with 5+ years specifically on IBM z/OS. Deep knowledge of JVM performance tuning on z/OS, including heap sizing, GC policies, zAAP/zIIP processor utilization, and WLM workloa .
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Most developer ads you'll see are written in English: 18,397 of the 24,795. That doesn't tell you whether the job itself requires you to speak English or work in English daily, so read each posting carefully. Don't assume the language of the ad matches the language of the team.
The employers posting the most developer roles are Link Group (369 jobs), Upvanta (257), jobgether (226), and OfferZen (212). If you're applying to any of these, research their hiring patterns. They move fast and post often, which means they're either scaling hard or replacing people who didn't fit.
In your interview, expect this: 'Walk me through the last time you had to debug something that took you more than an hour. What was it, what did you try first, and what would you do differently?' Hiring managers ask this to see if you think systematically or just try random fixes. Have a real example ready with specifics.