Keep background screen on display when using window keyword

I have a problem with loosing my initial screen when I display several
sequential windows on top of the initial display.  Here is the program
flow:

pgmA displays a full screen
pgmA calls pgmB
pgmB displays a window.  the user makes a selection and pgmB ends,
returning to pgmA
pgmA calls pgmC based on a parm received from pgmB
pgmC displays window

When pgmC displays it's window, the screen that pgmA displayed initially,
goes away.  I am using the RSTDSP=*yes on the screen in pgmA, and I am
using the ASSUME keyword in all 3 display files.

I have used windows in other applications and have had no trouble.  Is my
problem coming from the fact that 2 displays are being written over the 1st
display without any "rewrite" of the 1st display in between them?

Any suggestions would be appreciated.

Thanks,
John