This reports the amount of free space, in bytes, remaining in the node's uncompressed configuration memory. This is the uncompressed counterpart to cdx6500NMNPScmemSizeComp, and an admin comparing the two free-space figures can gauge how much benefit the node's configuration compression is actually providing, or whether a specific type of configuration change that doesn't compress well is eating into uncompressed headroom disproportionately. For example, uncompressed free memory shrinking much faster than compressed free memory would suggest recent configuration changes are of a type that doesn't compress efficiently on this node.