System and method for managing memory

A method and system for accessing data by an application program is disclosed. The application program issues a data request to a data storage system. In response, the data storage system loads into memory a data node corresponding to the data request. The data node is stored as part of a data structure. The data storage system returns a reference to the application program, which is then used to access the node. The application program may further instruct the data storage system to de-allocate a node when available memory is low or when it is no longer using the node.