Environment variables
Starting in version 5.11.0, caches can be controlled via environment variables.
All caches have a default length of 200000 and a default max age of 1800 seconds. These defaults can be overridden using the environment variables CACHE_MAX_LEN and CACHE_MAX_AGE_SECONDS respectively.
Values for specific caches can be set using:
DNS_CACHE_MAX_LENDNS_CACHE_MAX_AGE_SECONDSDNSSEC_CACHE_MAX_LENDNSSEC_CACHE_MAX_AGE_SECONDSSMTP_CACHE_MAX_LENSMTP_CACHE_MAX_AGE_SECONDS