Spaghetti stack
A spaghetti stack is an N-ary tree data structure in which child nodes have pointers to the parent nodes (but not vice-versa)
Spaghetti stack structure is used in situations when records are dynamically pushed and popped onto a stack as execution progresses, but references to the popped records remain in use. Following are some applications of Spaghetti Stack.
Compilers for languages such as C create a spaghetti stack as it opens and closes symbol tables representing block scopes. When a new block scope is opened, a symbol table is pushed onto a stack. When the closing curly brace is encountered, the scope is closed and the symbol table is popped. But that symbol table is remembered, rather than destroyed. And of course it remembers its higher level “parent” symbol table and so on.
Spaghetti Stacks are also used to implement Disjoint-set data structure.
Sources:
http://en.wikipedia.org/wiki/Spaghetti_stack