In this case, "stacking" is actually an old idea. Back when paper was scarce, and books were highly at risk, monks would memorize literally whole volumes of information by building a memory palace. Said palace was a whole interconnected series of mental rooms that had objects and decorations, with each item being associated with a particular piece if information. Whole speeches can easily be memorized this way.

For more information on this subject, try Thomas Harris' Hannibal, or