Following instructions to setup MVS in Hercules. One of the steps requires you patch a JCL file. It's just shy of 13000 lines. There are (long) instructions for doing it manually but, if you don't want to do that, there are scripts "that will do it for you".
A diff is also provided (called a "before and after comparison"). It's a 326 page PDF.
These old timers do things a little differently.