Except for some "Mickey Mouse" program, please don't use ACCEPT.
If you are using //SYSIN DD *, why not instead have your own DD Name, and just do the normal OPEN, READ, CLOSE. Means you can do things like check the FILE STATUS, know when your data has ended,
COBOL is not like languages you may be familiar with: you have to write code with COBOL, not just look for something that does it for you.
05 input-number pic 9(5).
05 input-rest pic x(67).
88 input-rest-is-ok value space.
IF NOT ( ( input-number NUMERIC )
AND ( input-rest-is-OK ) )
In this case you don't have to code much.