Warn if specified memory size is close to the default

Issue a warning to standard error if a specified memory size is within
10% of the default size.

Rework StackMemoryBucket so its default value is available like that
of other memory buckets.

[#52692569]
Merge 52692569-warn-if-memory-close-to-default to master

[Completes #52692569]
Merge commit 'e76b65f861f9ea3a7b8ae0aec2657d960a68c3fa'