in src/main/java/com/intellij/rt/debugger/agent/CaptureStorage.java [425:431]
public static String getCapturedStackForThread(int limit, Thread thread) {
Deque<CapturedStack> capturedStacks = storeAsyncStackTracesForAllThreads
? THREAD_TO_STACKS_MAP.get(thread)
: (thread == Thread.currentThread() ? CURRENT_STACKS.get() : null);
if (capturedStacks == null) return null;
return wrapInString(capturedStacks.peekLast(), limit);
}