z-Clamp setup

Hi
How woudt i aproch and init a Z Clamp
i got a large machine that has a heavy Z axis it has a Clamp system that acts on >500ms
the machine will most mill Flat things but shout be able of 2.5D
best way to my thought is to get the postprocess to output a UserMcode and G4 P0,5

is there a comp that can handle a Z Clamp on Auto so it releses bevore z move and clamps on XY movement

Thank you

I think I would use M64/M65 and let the Gcode trigger a relay to open and close the clamp.

its a mechanical clamp not a break
the relay is there
but i need to figure out best practice to run the machine as with Z move
i dont think it can make 3D parts like sculpting the Z will run over the Motor Torque 600mm/min is max to stop the Z axis on falling
and a ACC at 5mm/sec breaks also the mind if i go 8 it stalls on upmove i need more power 12Nm Steppers on Z