Once you've finished creating all the subplots (and you have the handles), you can set all of them at once by using :
set(AX_handles,'YLim',[A B])
Where AX_handles is a vector of axes handles, one for each subplot- for example:
for n=1:10
AX(n) = subplot(5,2,n)
end
A and B are your lower and upper limits. Finding the overall max will vary a bit depending on how your data is structed but it shouldn't be too hard.
