Hi Vimalraj,
To answer your questions in short - it is 16
VX(config-profile-HowManySSIDs-if-radio1)#
wlan X bss ?
<1-16> The bss number (
4 for ap300,
8 for {ap7602/ap7622}, {ap7612} and
{ap7632/ap7662})
But with more than 8 BSS you have to change the beacon period and performance will significantly drop once you hit more than 6 BSS!
You shall always aggregate WLANs into same SSID and rather use VLAN assignment (RADIUS or CP).
See my favorite
SSID overhead calculator
Regards,
Ondrej