TRAIL indicates to keep trailing blanks on fixed length records. SBSENDEOL can be CRLF, CR, LF, or NONE This SITE command sets the Single Byte end-of-line character sequence; if it is CRLF and you're not sending both then the lines would be truncated by a byte. If you can ftp to the mainframe, QUOTE HELP SITE should give you the SITE parameters you can use.