I got over 2Gb size file to load. I got "SQL*Loader 500: Unable to open file" and "HP-UX Error: 72: Value too large to be stored to data type" error messages.
I have HP-UX 10.20 with large file option for this particular filesystem and Oracle 7.2
I searched metalink and found your error. Oracle instructed the person to contact HP support.
HP support said it's Oracle bug and should be patch #612534 but I failed to find the patch on metalink.
A patch for 7.2 probably isn't on metalink. The analyst will probably have to place it there or send it to you.