The proximity from self parameter is available from release 13.1 build 48.x onwards.
When you configure the static proximity load balancing method, a server is chosen based on the client IP address instead of the NetScaler loopback IP address. As a result, the response time might be higher. The parameter proximity from self when enabled, ensures that the request is sent to a server that is closest to the NetScaler by using the NetScaler loopback IP address. Setting this parameter to YES accelerates the response time if the servers are located closer to the NetScaler as compared to the client.