zOS, OS/390, Perl, and ancestors

A relevant piece of "Real Programmers Don't Use Pascal" comes immediately to mind: "No, your Real Programmer uses OS\370. A good programmer can find and understand the description of the IJK305I error he just got in his JCL manual. A great programmer can write JCL without referring to the manual at all. A truly outstanding programmer can find bugs buried in a 6 megabyte core dump without using a hex calculator. (I have actually seen this done.) OS is a truly remarkable operating system. It's possible to destroy days of work with a single misplaced space, so alertness in the programming staff is encouraged. The best way to approach the system is through a keypunch. Some people claim there is a Time Sharing system that runs on OS\370, but after careful study I have come to the conclusion that they were mistaken." And, anyway, wouldn't MVS, OS/390 or zOS, or whatever IBM marketing is calling it this week run Perl just fine under its POSIX layer (OMVS)? <snip>