MinSpareThreads/MaxRequestWorkers

[mpm_event:error] [pid 612370:tid 140113121235520] AH10159: server is within MinSpareThreads of MaxRequestWorkers, consider raising the MaxRequestWorkers setting.

Where is the location of Apache's MinSpareThreads and MaxRequestWorkers configuration files ?

Even though Apache is running, access to the website cannot be reached. CPU drops to low, Apache is running, but access to the site is not working. I have to restart Apache before the site returns to normal, and i have to restart continuously to make the site normal. How to solve this ?

You can put those directives in the main httpd.conf or in a vhost conf file if it's only needed in that context. You won't find examples already in the conf files -- you'll have to draw from the documentation or from other online examples.