The MaxSpareServers is exactly the opposite of the MinSpareServers directive. Whereas you use the MinSpareServers directive to specify the minimum number of spare servers to be maintained in the process pool, you use the MaxSpareServers directive to specify the maximum number of spare servers that need to be maintained in the process pool. The default value specified for this directive is 10. This directive specifies the upper limit for servers that can remain idle in the process pool. The fact that Apache is receiving fewer requests might result in many idle server processes in the process pool. More idle server processes hog the system memory without serving a purpose. So, the best approach is to specify a higher limit for idle server processes. The main Apache server “kills” the idle server processes above the specified limit.
The default value for this directive is seldom changed, and any changes there are depend on the load on the server. For production servers with very high traffic, you can increase the number of maximum spare servers. On the other hand, for servers on the local area network, keep the maximum limit as is or reduce it for servers handling light loads.