The more I dig into this, the more I learn (duh). Looks like I am definitely limited to 44x66 inches as my largest canvas for a custom size. Since the Z3200 doesn't have any large standard sizes, I am stuck. Time to put the print job on my iPF8100, I guess.
What doesn't make sense is that the printer driver allows you to click print, even though the job never gets sent to the spool. I didn't notice the small, blue warnings on the right hand side, and these have to be read and cleared somehow before the print job will actually go through.
There were length limits with the plain Z3100 at 109" and something like 129" but never at numbers below that. The Z3200-PS goes way beyond that with the PCL3 driver and despite the 129" limit present in the paper size menu of the PS3 driver that one also should go beyond 129" according to a message on this forum. I think the plain Z3200 should at least do 109" and probably more. The optional HPGL2 driver will extend the length beyond that.
met vriendelijke groeten, Ernst Dinkla