stack up
To put into a stack.
Stack up the boxes.
ADV
carefully, neatly
away, up
She stacked up the clean plates in the cupboard after washing the dishes.
PREP
against
The old wooden chairs were stacked against the garage door for storage.
in
The old boxes were stacked in the garage until we had time to sort through them.
on
The children stacked their books on the shelf before leaving the classroom.
with
The garage was stacked with old furniture that we no longer needed.
PHRASES
be stacked in piles
The old books were stacked in piles on every shelf in the library.