Limestone stackers are used to make piles of Limestone for storage. Run a conveyor like 'Conveyor 01' (kuid2:124017:10126:1) to the top for Limestone delivery. Often there is an underground auger and conveyor system for removing Limestone from the pile, so you might also run a conveyor out from the bottom somewhere.
You can set the height of the Limestone pile with the 'Edit Properties' tool from Surveyor's 'Objects' tab.