I need your help on this problem urgently. When i run a SQL query in Oracle on the Production Server, it is giving me this error. What should i do ?

ERROR: SQL code, error message: -1 ORA-04030: out of process memory when trying to allocate 16384 bytes (sort subheap,sort key)

This is happenning only on the Production Server. When i execute the same query on the SIT Server, it does not give me the above error and executes in a few seconds. I checked the SGA and other Oracle settings of both the servers and did not find any difference. Can you please help me out.