Stacking

When you have a stack of something, what comes to mind is usually a long pile of objects placed in a directly vertical fashion, which often resembles some sort of tower. I was having a ridiculous argument with a friend of mine who continued to believe that a stack (of blocks we'll say) can be organized in a horizontal fashion creating a horizontal stack. I don't believe this is true because when things are "stacked" horizontally it's usually just to start another vertical stack.