Mainframe, MVS and zOS Discussion

This usually happens because very large COBOL copybooks (often flattened or vendor-supplied) make the Git pack huge, and git push times out on Rocket Git. A few workarounds:

• Avoid committing flattened copybooks — DBB/zAppBuild can resolve nested COPYs via copybookSrcDirs, so keep only modular copybooks in Git. If flattening is needed, generate it in the build step, not in version control.
• Use SSH instead of HTTPS to bypass proxy/LB timeouts.
• Tweak Git client settings: lower compression (core.compression 1) , raise timeouts (http.lowSpeedTime 600), and repack before pushing.
• Consider Git LFS (if supported) for large, rarely changed copybooks.
• Infra fix: increase reverse-proxy/load balancer timeouts (NGINX/Apache/ALB).

In practice, the cleanest approach in DBB pipelines is to keep Git light (just source + modular copybooks) and fetch any large/vendor copybooks separately during the build.

 

Rocket Git for z/OS is Rocket Software’s port of the popular Git version control system to the IBM mainframe environment. It gives mainframe developers the same benefits that distributed developers enjoy with Git—tracking changes, managing versions, and collaborating on code—but tailored for z/OS. One of the standout features is its handling of character encoding: since mainframe code is usually in EBCDIC (like IBM-1047) while most modern tools use ASCII, Rocket Git automatically translates between the two via .gitattributes, making cross-platform work much smoother. It also integrates well into DevOps pipelines, enabling Git-based workflows and helping organizations modernize their mainframe development practices. Overall, it’s part of Rocket’s broader push to bring open-source tools to the mainframe world, lowering barriers and making the platform more accessible to a wider pool of developers. You can also check IBM’s official page here for more details: IBM Rocket Git for z/OS.