Although I consider table reservations to be a bottleneck and advise avoiding them whenever possible, it is possible to use them in IBX. Dan Palley posted this explanation on how to do it:
Table reservations aren’t used much, as you can see. The order is critical and it’s not well documented anywhere. Here’s how I’m doing it:
isc_tpb_nowait isc_tpb_lock_read=INVOICE isc_tpb_protected
I think you can omit the isc_ from the lines, but it should work with them as well.
Note: The lines above go into your TIBTransaction.Params property.
Update: Dan didn’t think the warning above is strong enough. Table Reservations should only be used when all other options have been exhausted.