C<SPVM::Native::Stack> is the C<Native::Stack> class in the L<SPVM> language.
The instance is a call stack. It hasinformation of the call stack.
An instance of the C<Native::Stack> class is build by the L<new_stack|SPVM::Native::Env/"new_stack"> method in the L<Native::Env|SPVM::Native::Env> class.