The callstack would be the function calls listed in the crash reporter window when it pops up. As an example:
UE4Editor_Engine!USceneComponent::OnComponentDestroyed() scenecomponent.cpp:680
UE4Editor_Engine!AActor::MarkComponentsAsPendingKill() actor.cpp:3723
UE4Editor_Engine!UWorld::DestroyActor() levelactor.cpp:640