A record-level checksum seems like belt-and-braces-made-of-titanium-wolfram-diamond-and-then-hardened. Ultra-security? You have to kill me if you tell me what it is for?
Assembler? Presumably you prepare the file by extending the lrecl prior to the sort?
If you append to the record, you're making it more "difficult" to find, but again I'd guess you are going to read them in Assembler?
With the Fixed, again you'd need to pre-extend the records. Maybe that gives you a good moment to make them variable?
I've previously looked a little at getting length for a fixed file to the exit. I couldn't find anything that convenient, doesn't mean the DFSORT experts won't have some ideas later.
To make it worth making it generic, I guess you're looking at using for a number of datasets? Else why bother?
Interesting. You doing a simple hash? Whoops... forget I asked that, I have family...