Ceiling on the spares held for this label, and therefore on how far the spare target can climb while the label cannot keep up. It applies to the label group as a whole, so a maximum of 3 means three spares spread over every AMI carrying the label, not three per AMI.

Leave blank for no ceiling, in which case the target follows the label's load however large that grows, limited only by the instance caps. Set it if the cost of a wide parallel build warming an equally wide pool of spares is a concern.

This can only lower the number of spares, never raise it: each AMI's Instance Cap and the cloud-wide cap still apply, so a template already at its cap is skipped even when this maximum is higher.