Use the RECLEN command to indicate the length of a fixed-record-length file or the maximum record length of a variable-record-length file. If the file being sent does not have a record structure, then this command is not meaningful.
The RECLEN statement must come after a FILE command and should preceed any DATA commands.

The syntax is
  RECLEN     record length  

record length   is the record length
(must be a whole number)

A receiving system may reject a file with a RECLEN that is too large for it to handle. Depending on how the file is to be processed, the destination subsystem might not be able to handle the given RECLEN, such as an SMTP gateway, for example.