title: Conserve /proc/PID/ after process exists
body: <p>I want the /proc/PID/ directory of a process to be conserved for some time even after the exit of the program ,so that its "grand parent" can check out the resource usage from /proc/PID/stat. I can't use wait4() since I am concerned about the resource usage of "grand cild". So how can I conserve the /proc/PID/ directory?</p>
  
  <p><strong>NOTE</strong> : Copying the /proc/PID/stat just before exiting the program is not a solution in my context,since I need the total resource usage statistics of  that process throughout its life time.</p>