Stacking is when the draw weight per inch becomes increasingly harder the further the bow is drawn. I had an old Herters 60" bow that was 55 @ 28 and I was trying to draw to 32 inches. Man, it was a killer. I felt like I hit "the wall" at about 30 inches and the bow wanted to explode.
I'm no expert but I think around 3 lbs. per inch of draw is normal for most bows, so your last two inches your bow is increasing at 7 lbs. per inch. yes, that is stacking, and if you have to draw that far to reach your proper draw length, yes it is bad and you will probably find it uncomfortable.
I now shoot a 64" Black Widow PMA II that draws comfortably out to my 32" in draw without stacking. Makes a world of difference for me.