file: /proc/sys/net/ipv4/cipso_cache_bucket_size
variable: net.ipv4.cipso_cache_bucket_size
Official reference

The CIPSO label cache consists of a fixed size hash table with each hash bucket containing a number of cache entries. This variable limits the number of entries in each hash bucket; the larger the value the more CIPSO label mappings that can be cached. When the number of entries in a given hash bucket reaches this limit adding new entries causes the oldest entry in the bucket to be removed to make room. Default: 10