overflow pdl [MIT] n. The place where you put things when your pdl is full. If you don't have one and too many things get pushed, you forget something. The overflow pdl for a person's memory might be a memo pad. This usage inspired the following doggerel:

     Hey, diddle, diddle
     The overflow pdl
        To get a little more stack;
     If that's not enough
     Then you lose it all,
        And have to pop all the way back.
                                    --The Great Quux

The term pdl seems to be primarily an MITism; outside MIT this term is replaced by `overflow stack'.