Data written to the CELQPIPI MSGRTN file is always appended to
the end of the file.
When the data written is longer than 255 bytes, it is written
to the CELQPIPI MSGRTN file 255 bytes at a time, with the last write
possibly less than 255 bytes. No truncation will occur.
When the output data is shorter than the actual LRECL of the CELQPIPI
MSGRTN file, it is padded with blank characters by the z/OS Language
Environment system write interface.