chap lists and arrays revisited freelist figure example of lisp list variablesincluding the system freelist int[ new int[ ]int[ new int[ ] qwhile in java this would be no problem (due to automatic garbage collection)in languages such as +this would be considered bad form because the original space allocated to is lost as result of the third assignment this space cannot be used again by the program such lost memory is referred to as garbagealso known as memory leak when no program variable points to block of spaceno future access to that space is possible of courseif another variable had first been assigned to point to ' spacethen reassigning would not create garbage some programming languages take different view towards garbage in particularthe lisp programming language uses the multilist representation of figure and all storage is in the form either of internal nodes with two pointers or atoms figure shows typical collection of lisp structuresheaded by variables named aband calong with freelist in lisplist objects are constantly being put together in various ways as temporary variablesand then all reference to them is lost when the object is no longer needed thusgarbage is normal in lispand in fact cannot be avoided during normal processing when lisp runs out of memoryit resorts to garbage collection process to recover the space tied up in garbage garbage collection consists of examining the managed memory pool to determine which parts are still being used