It's the same as a multistatement in BTEQ, just search for multistatement in SQL Manual, Vol. 1
A typical example is several Insert/Selects into an empty table: If you use seperate requests, the first one will be fast, because the table is empty and the insert will need no Transient Journal. But the next Insert is into a table with data, so it's using the TJ.
If you use a multistatement instead *all* Inserts run without TJ.
Dieter