Where does sp_trace_getdata store its information, and how do i set the size of the buffer is uses?

We are using sp_trace_getdata to run a trace against SQL Server. Unforutnately this call seems to be undocumented.

Where does this call store the trace data it produces? Does it write to a buffer in memory?

We are also hitting trace rollover events. Is there a way to increase the buffer size sp_trace_getdata uses to try to limit these?