The Shulhan Aruch (Y"D 282) tells us that one should stack certain books in a certain order (e.g. Humash on top of a Sefer Navi). What is the Din of a Siddur for this purpose?
My friend told me he asked a very famous Posek who said that a Sidur has the same status of e.g. a Sefer Musar. Today I was told that my Rosh Yeshiva holds that it has the status of Sefer Tehilim.
What do the sources have to say?
(I'm asking only according to the opinion that applies the stacking rules of the Gemara/Shulchan Aruch to printed and bound books.)