[ASM] : "Request length exceeds defined buffer size " - How to increase the limit ?

Hi Experts , 

WAF is rejecting the request because it exceeds the maximum allowed request size (10MB)

Requested URL : [HTTPS] /stock.option

Host : trade-it.ifund.com

Detected Request Length : 12005346 bytes ( 12 MB )

Expected Request Length : 10000000 bytes ( 10 MB )

How to increase the limit specific to this url/uri only ?