Httpd should be able to use bigger keys for secure connection.
OpenSSL is updated to version 1.0.2h allowing to append newly generated DH_PARAM key to default certification file localhost.crt.
After installing httpd and running .postinstall script use few more commands to extend default certification file if need.
Run openssl provided by zip/rpm package with "<path_to_provided_openssl_folder>/openssl dhparam -out dh_2048.pem 2048" for generating DH_PARAM with 2048-bit key.Content of dh_2048.pem append to localhost.crt created by .postinstall script (httpd/conf.d/ssl.conf should show you proper destination of file). Now start httpd server.
Server starts with extended Server Temp Key: DH, 2048 bits. You can verified it by running "<path_to_provided_openssl_folder>/openssl s_client -connect localhost:443 -cipher DHE-RSA-AES256-GCM-SHA384".