[PD] stack component

[federico]

hi all,
is there a stack component for pure-data?
my search thru the pd-list and pd-database returned zero results.

i'm developing a monophonic synth with portamento, and i would like to 
emulate the classic portamento behavior that most (monophonic) 
synthesizers have. i.e.:
i hit C3: osc plays C3
i hit F3 (without releasing C3): osc slides to F3
i release F3: osc slides to C3

in order to achieve this, i need the classic stack container, with 
methods push (for note press) and pop (for note release).

which component is more appropriate for this (if it exists)?
otherwise, how this can be implemented?

thanks!

-- 
Federico