What is single processor implementation in data structure ?

Single Processor Implementation (Storage Areas)- When a subprogram is called in one processor, it must have a storage area; it must save the registers or whatevers else it will change, using the storage area also for its return address calling parameters, and local variables. As it returns, it will restore the registers and the other storage that it was expected to restore After the return it no longer needs anything in its local storage area.
In this way we implement subprogram calls by changing storage areas an action that takes the place of changing processors In these considerations it really makes no difference whether the subprogram is called recursively or not, providing that. in the recursive case, we are careful to regard two recursive calls as being different so that we do not mix the storage areas for me call with those ofanother, any more than we would mix storage areas for different subprograms one called from within the other.