'A mapping from database names to registries.'

@lazy_classproperty
def registries(cls):

    size = config.get('registry_lru_size', None)
    if (not size):
        if (os.name != 'posix'):
            size = 42
        else:
            avgsz = ((15 * 1024) * 1024)
            size = int((config['limit_memory_soft'] / avgsz))
    return LRU(size)
