It's usable, but a little different. I mean the guys at Rocket Software have ports of some of the basic unix packages for z/OS including the Bash Shell, just adding that to USS improves quality of life tenfold. Many features are doable through USS but ISPF will always be the main interface.
There are ways to develop in Eclipse that can target z/OS.
https://developer.ibm.com/zsystems/documentation/java/jzos/j...
https://www.ikanalm.com/solutions/devops-and-toolchain-orche...
However, the people who develop for z/OS are often people who are familiar with Interactive System Productivity Facility (ISPF). It's a bit like whether people who are proficient in Vim or Emacs really benefit that much from an IDE.
There is also a unix shell with a z/OS interface:
https://www.ibm.com/support/knowledgecenter/zosbasics/com.ib...
But again, the people who program mainframe learn it through that environment. It would be interesting to hear from people who have used these sorts of set ups.
You're not alone my friend, those IBM docs certainly are not easy to read/understand.
Just as for Unix, Linux, Windows, and so on, there's an IBM "culture" (terminology, conventions, etc.) that you have to get used to. (It often helps to know some of its history, too.) But since I grew up professionally with one foot in the IBM world I usually don't have much trouble at all reading their docs.
Hehe, I once ran tail(1) and forgot to enter the file name, so tail read from stdin, and Ctrl+D did not work, so my shell was stuck waiting for input until the system was IPL'ed. Fun times... ;-)
I once spent three days figuring out how to deal with an invocation that did not fit in an 80-character line. sigh
(Rexx has since developed an object oriented dialect, that might be more convenient to use.)
For whom? They shouldn't necessarily spend a bunch of effort adapting their product towards the Unix world, particularly to the extent it compromies their product for their primary customer base.