t-kamal Gen only generates Java from the Windows workstation or from the distributed Client / Server Encyclopedias that run on Windows, AIX or HP-UX. However, that Java can run on any platform that has a Java Virtual Machine and a Java Application Server such as Web Sphere, Web Logic or JBoss / Wildfly (for EJBs) or HTTP server such as Tomcat (for java web clients).
CA does have at least one client running Gen-generated Java EJBs under Web Sphere on z/OS. Those EJBs were formerly CICS COBOL servers that were re-platformed to Java EJB. CA created a prototype to generate Java from a z/OS Host Encyclopedia for this customer but there has not been enough customer interest as yet to actually make that a GA product as yet. See the discussion on the EDGE community site.
What is the purpose of your question? What problem are you trying to solve?