If you google "utilityname sample jcl" when you need one, you'll usually get some good results.
However, if your site is full of standards, I'd check with colleagues first: do it the way your site does it.
There are DD names which have specific names and which conventionally serve a specific purpose.
Like STEPLIB, SYSIN, SYSOUT, SYSUTn, SORTIN, SORTINnn, and many more. Not thought about it before, but mostly beginning with S
You need to use those where they are needed, and where others are needed from applications you are running, you need those as well.