Allocation and Deallocation

I am having extreme difficulty understanding the memory management system of Zend. The Cocoa frameworks, for instance, have very defined guidelines and methods for when objects should be allocated and deallocated. However, the Zend engine seems to have a great many inconsistencies. What is the concept behind Zend's allocation, deallocation, and referencing schemes. When must I deallocate, when must I copy, when must I reference, and what functions do I use? Thank you kindly, Witten