Okay, here's the deal. I've got a tab delimited file that used to load perfectly fine into file using the CPYFRMIMPF command, using the following options;
CPYFRMIMPF FROMSTMF('/Directory of file/file.txt') TOFILE(Library/file) MBROPT(*REPLACE) RCDDLM(*CRLF) STRDLM(*NONE) RMVBLANK(*NONE) FLDDLM(*TAB) RPLNULLVAL(*FLDDFT)
After much research, I'm pretty sure that the issue lies in the changes to the CPYFRMIMPF command in the V5R3 upgrade, since this is the only event that occured between the upload working and not working properly. The majority of records load without an error, but a few thousand don't make it to the AS400 file, and within the job log there is this error;
"Copy did not complete for reason code 7."
I've been informed that loading a PTF is NOT an avenue that I can pursue (even though I've found information that this would fix the problem!)