smb.conf is a configuration file used for the open-source SAMBA software.
Apple have not used SAMBA software since they launched OS X 10.7 Lion. Due to a change in the license terms SAMBA uses Apple felt unable to continue to work with those license requirements and have instead written their own implementation from scratch which is generally called SMBx. Being totally different software it uses totally different means of configuring it.
Some of the files it uses for configuration are as follows
/Library/Preferences/SystemConfiguration/com.apple.smb.server.plist
/System/Library/LaunchDaemons/com.apple.smbd.plist
~/Library/Preferences/nsmb.conf
/etc/nsmb.conf
If you do 'man nsmb.conf' and 'man smbd' in Terminal.app this may be of particular help.