Issue with large data in SSRS

Hi,

   In a current SSRS project I am working on - we get the data from sql server as per some id value and populate the data in a shared dataset and then set a parameter and from the parameter we set the datset corresponding to some rdl.In 1 of the rdls,the data comimg from the sql server is more than 20 mb and we get a memory out of exception.Do we need to increase the size of the default datset and the parameter?Please provide some solution.It's really very urgent.

Thanks and Regards,

Sandip