CURLMOPT_MAX_TOTAL_CONNECTIONS man page
CURLMOPT_MAX_TOTAL_CONNECTIONS — max simultaneously open connections
CURLMcode curl_multi_setopt(CURLM *handle, CURLMOPT_MAX_TOTAL_CONNECTIONS, long amount);
Pass a long for the amount. The set number will be used as the maximum number of simultaneously open connections in total using this multi handle. For each new session, libcurl will open a new connection up to the limit set by CURLMOPT_MAX_TOTAL_CONNECTIONS(3). When the limit is reached, the sessions will be pending until there are available connections. If CURLMOPT_PIPELINING(3) is enabled, libcurl will try to pipeline or use multiplexing if the host is capable of it.
The default value is 0, which means that there is no limit. It is then simply controlled by the number of easy handles added.
Added in 7.30.0
Returns CURLM_OK if the option is supported, and CURLM_UNKNOWN_OPTION if not.
CURLMOPT_MAXCONNECTS(3), CURLMOPT_MAX_HOST_CONNECTIONS(3), curl_multi_setopt(3).