code: public void setSystemMessageValue(long value) {
          if (TraceComponent.isAnyTracingEnabled() && tc.isEntryEnabled())
              SibTr.entry(this, tc, "setSystemMessageValue", Long.valueOf(value));
          // Clear the cached MessageHandle
          cachedMessageHandle = null;
          // Set the value into the message itself
          jmo.setLongField(JsHdrAccess.SYSTEMMESSAGEVALUE, value);
          if (TraceComponent.isAnyTracingEnabled() && tc.isEntryEnabled())
              SibTr.exit(this, tc, "setSystemMessageValue");
      }
docs: /*
  Set the value of the SystemMessageValue field in the message header.
  
  Javadoc description supplied by JsMessage interface.