The HOLD statement has the form
HOLD device,device,device,...device
and inhibits, for parallel processes subordinate to the main program, device not open errors for the devices whose numbers are given (device may be any integer-valued expression). Instead, processes attempting input/output on these devices when they are not open are simply to be caused to wait until they are available.
This will not work for parallel processes executing sequentially rather than concurrently on serial machines.