RowCacheSize - when to set ?

[Steve Baldwin]

Can someone please tell me if the RowCacheSize needs to be set before
calling 'prepare' or before calling 'execute' if I want it to be
effective for a SELECT statement.  I'm using Oracle, so I know it is
supported, but the RowsInCache statement handle attribute returns undef,
so it's difficult to work out when to set RowCacheSize.  And yes, I did
read the fine manual but couldn't find an answer to this question.
 
Thanks,
 
Steve