Does Z-Stack (or TI-RTOS) have reserved events for Semaphore_pend()? Periodical event 0x8000 is detected.

I use one of Z-Stack examples for our project and see the strange periodical event 0x8000 in zcl_samplesw.c function zclSampleSw_process_loop() that were not produced by our application. It looks like the event parameter "appServiceTaskEvents" 0x8000 is changed internally by TI-RTOS and triggers the loop process. I can't find where it goes from.

What does the event 0x8000 mean and if there are any other registered events?

/*******************************************************************************
 * @fn      zclSampleSw_process_loop
 *
 * @brief   Application task processing start.
 *
 * @param   none
 *
 * @return  void
 */
static void zclSampleSw_process_loop(void)
{
    /* Forever loop */
    for(;;)
    {
        zstackmsg_genericReq_t *pMsg = NULL;
        bool msgProcessed = FALSE;

            /* Wait for response message */
        if(Semaphore_pend(appSemHandle, BIOS_WAIT_FOREVER ))
        {
            /* Retrieve the response message */
            if( (pMsg = (zstackmsg_genericReq_t*) OsalPort_msgReceive( appServiceTaskId )) != NULL)
            {
                /* Process the message from the stack */
                zclSampleSw_processZStackMsgs(pMsg);