Which of the following processes is needed to load a mainframe operating system? 05/22/2020 – by Mod_GuideK 0 Which of the following processes is needed to load a mainframe operating system? A. TSO/E B. IML C. JES D. IPL SHOW ANSWERSCorrect Answer: D Explanation/Reference: Download Printable PDF. VALID exam to help you PASS.