I just had a call open today on this very issue. It appears as if things have changed somewhat in 8.9 and above. In XE and ERP 8 you could do the following:
[DB SYSTEM SETTINGS]
SQL Package Library=Number
If the number is 1, the sql package will be created in QTEMP.
(Creating them in QTEMP effectively deletes them as they are used).
If the number is 0, the sql package will be created in the library
specified in [INSTALL] under DefaultSystem. If there is no Default system specified, they will go to QGPL.
However in 8.9 and above the following applies:
[DB SYSTEM SETTINGS]
SQL Package Library=Number
If the number is 0, the sql package will be created in the library
specified in [INSTALL] under DefaultSystem. If there is no Default system specified, they will go to QGPL.If the number is 1, the sql package will be created in QRECOVERY.
If the number is 2, the sql package will be created in QRECOVERY with some extra logic to make sure that UBE and TC work with ALTER TABLE Command properly.
My thought was to set the DefaultSystem=QTEMP and the SQL Package Library=0 but I have not given it a try yet.
The problem with them being created in QRECOVERY is that they are not deleted automagically.