code: protected function pushStack($funcName)
      {
          $this->funcStack[] = array(
              'function' => $funcName,
              'tsStart' => $this->timeLastTick,
              'subTime' => 0,         // how much time spent in nested functions
          );
          if (!isset($this->data[$funcName])) {
              $this->data[$funcName] = array(
                  'calls' => 0,
                  'totalTime' => 0,   // time spent in function and nested func
                  'ownTime' => 0,     // time spent in function excluding nested funcs
              );
          }
          $this->data[$funcName]['calls'] ++;
      }
docs: Add function to call stack
  
  @param string $funcName fully qualified function name
  
  @return void