I glanced at this and ended up spending 20 minutes reading it and I regret nothing: https://www.wealthsimple.com/en-ca/magazine/cobol-controls-your-money
(Mostly of geek interest: About the continuing survival/blessing/curse of COBOL)
This. I learned COBOL in college. It's not super hard. The issue here isn't the language. The issue is "hey - we have a code base that is mission-critical, and has grown over the years, implements some ugly financial procedures that you may not understand, and none of the original folks who understand it are still around, and if you screw it up it could cost millions"- the language is *irrelevant*. I'd hesitate to touch something with those specs written in any language, not just COBOL.
@Biggles @dagon @timbray
COBOL and JCL are not difficult languages to learn.
The problem is that any given *system* is *thousands* of those programs interacting in all kinds of subtle and complex ways.
And that COBOL, as a language, is so limited that thousands of subtle dependencies between far-flung programs are inevitable. Finding all of them impossible. And any failure can kill the whole business.