File status 39 - program fine or JCL wrong?

Program abends on OPEN with file status 39. COBOL FD says LRECL 200. JCL DD looks right to me. Senior dev says check JCL first on status codes.

What is the fastest way to prove whether this is a JCL mismatch versus something in the SELECT?

LISTDSI or ISPF browse on the actual data set for LRECL and RECFM. Nine times out of ten the JCL DCB does not match the catalog.

Catalog said 250. JCL had 200. FD was 200. Fixed the DCB in JCL. Running.