MemorySegment.allocateNative(1024, SegmentScope.auto()).scope().isAccessibleBy(Thread.currentThread()) returns false.
Similarly
MemorySegment.allocateNative(1024, SegmentScope.global()).scope().isAccessibleBy(Thread.currentThread()) returns false too.
From documentation of SegmentScope.auto(), SegmentScope.global(), the returned scope object is accessible by any thread.

Arena.openShared().scope().isAccessibleBy(Thread.currentThread()) returns false. Though shared scope documentation doesn't explicitly state accessibility by multiple threads, the result is counter intuitive