Ice AMI Callback Object Lifetime

A call to an AMI method requires a callback object that implements the output side of the AMI request. Easy enough. The example on page 870 in the manual looks like this:

Demo::ModelPrx model = ...;
AMI_Model_interpolatePtr cb = new AMI_Model_interpolateI;
Demo::Grid grid;
initializeGrid(grid);
model->interpolate_async(cb, grid, 0.5);

The AMI_Model_interpolatePtr variable cb will fall out of scope at the end of the routine and be destroyed. Since the callback object pointer is passed into the _async request and it holds a pointer to the callback object instance, so will the callback object itself will be automatically destroyed by the Ice runtime after ice_response or ice_exception has been called?

In section 31.3.4 of the manual (Concurrency Issues), the first bullet point states that a callback object must not be used for multiple simultaneous invocations, and I'm guessing this is because one thread could destroy the callback object before the second one called it?

TIA