Pool Size Exceed Limit -SAP adapter

We have SAP adapter with pool size equal to 30 but I am getting following error at my integration server:

com.sap.mw.jco.JCO$Exception: (106) JCO_ERROR_RESOURCE: Number of connections in pool MINDSPEED-PROD&EBIZCPIC2&;&017&EN; exceeds limit of 20

Please let me know why these errors are coming out although max pool size is still greater then 20. Is it something related to �Peak Size�? How can we edit Peak Size?
I will appreciate any help regarding it.

Thanks & Regards