For example FULL(x, y, z), what are the ideal values for x, y and z?

ummm. maybe there is an ideal setting but it may all be relative. I use 10,5,5 but its relative. What I mean is this ? Individual currencies will have their idiosyncrastic stochs pattern. So read the stochs pattern in relation to the price pattern. After a while you will have a "gut feeling" of where the sentiment is relative to the stochs. The other thing I found interesting was , by studying the stochs pattern on 3 different time frame gives a more predictable outcome. eg, if on the daily the stochs is already cutting down but on the hrly the stochs is actually turning up but the hourly is turning up. By just looking at the daily I will open a short position, but becasue the 8hrly and hrly is turning up I hold back and maybe actually open an intraday long position.

Honestly, full stochastics are a lousy indicator in Forex. I tested them and trust me on this one: stochastics simply don't work.