AM335x DMTIMER Interrupt

Hi,

I have a question about AM335x DMTIMER interrupt.

The DMTIMER interrupt will be occure when counter overflows.
In ISR of this interrupt, I'm doing only following process.
*****************************************************
void DMTIM_ISR(void)
{
	1.Clear IRQSTATAUS Register "OVF_IT_FLAG" by writing '1' to this bit
	
	2.Set '1' to INTC_CONTROL Register "NewIRQAgr"
	
}
*****************************************************

To avoid interrupt by itself, 
do I also need to configure INTC_THRESHOLD Register to mask the same interrupt?

In the AM335x Starterware DMTIMER example program,
it disabling DMTIMER interrupt at the top of the DMTIMER ISR function,
and enabling at the end of ISR. Do I must disable/enable DMTIMER interrupt in ISR?

best regards,
g.f.