Guardian Procedure Calls Reference Manual (G06.25+)

Introduction to Guardian Procedure Calls
Guardian Procedure Calls Reference Manual—522629-013
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Bounds Checking of Reference Parameters for
Guardian Procedures
Those Guardian procedures that use a different local data stack copy the caller’s
parameters to that stack before proceeding. Because the reference parameter does
not then intrude into the Guardian procedure’s local data stack, it does not cause a
bounds violation error. It is possible, however, that the process will abnormally
terminate on return from the called Guardian procedure, because it might have written
over the return address that was stored in the local stack.
Which Guardian procedures actually switch stack might change from release to
release and will differ by processor type.