LRECL may not be the only thing, you might want to check the Block size and record format (may not make a difference). I'm assuming you are issuing a SITE command to set the Record Length, Block Size, Record Format as well as Unit (not quite sure what this is or does). Also you might need to issue another SITE command for "trail" (not sure what this does exactly. This is based on some code I have to send files to a mainframe (not sure if it is a Z/OS or what - the code is based on something the mainframe guys gave me so I could FTP to them without having data being truncated).