What is ViewState Chunking
Size of hidden viewstate have no limit.some poxy and firewalls refuse page loads if they have hidden file have greater than certain size. to solve this problem by viewstate chunking.ViewState Chunking is automatically divide view state multiple field to ensure that no hidden field overcome max size. viewstate chunking is not a method for good performance, its only for some proxys and firewalls.
for viewState chunking u can set the maxPageStateFieldLength attribute of the <>
element in the web.config file
< maxpagestatefieldlength="1024">< / pages >
< /system.web >