mathematical optimization – Minimization of constrained variable

I am trying to perform a minimization of a variable but NMinimize() does not seems what I need (it minimize a function, but my variable is inside a function)

I want to minimize “h” with respect to “P0” and “yp” with the following constraints:

 c1 <= F(h,P0,yp) <= c2
 c1 <= G(h,P0,yp) <= c2
 c1 <= H(h,P0,yp) <= c2
 c1 <= J(h,P0,yp) <= c2
 h>c5
 P0>0
 c3<yp<c4

I tried:

 NMinimize({h,constraints},{P0,yp})

but it does not work.

h,P0,yp are all variables and not functions.