I read it somewhere just now about it (I myself asked it in my earlier post though) and thought might help some else also:
"
One stop bit-time is recommended.
If the RS-232 cable is very long then two stop bit-times may be needed.
You may occassionally see 1.5 stop bit-times. The intent is to gain 4% more data throughput when a link is too long for one stop bit-time but is too short to require two stop bit-times. 1.5 stop bit-times is now rare enough to be a hazard to use
"