This week's book giveaway is in the OCPJP forum. We're giving away four copies of OCA/OCP Java SE 7 Programmer I & II Study Guide and have Kathy Sierra & Bert Bates on-line! See this thread for details.
The Stack under java.util extends Vector instead of a LinkedList.
Vector is a resizable array. So, from what I know, it should make it heavy on memory management.
Also, we’re interested only on the top element of the stack. By using an linked list, we can get away with just one pointer.