Hi Roberto,
1. Reason for not asking to create the tablespace could be that tablespace in systems might not be correct even before starting the upgrade. For eg. you have a 740 source release system and dont have any 740 specific tablespace then it might not ask. You should make sure that these are correct before starting the upgrade.
2. In system switch upgrade, the switch of tables happens with rename command. You can find more details in EUSWITCH log files. You will see command like "rename <table>~ to <table>" so tablespace are not involved in switch or command.
3. Normally,If your source release and target release is same then it will add/delete 'X' at the end of release specific tablespace.
example: A series of sp update will cause the below changes. Lets assume my current release is 740 and I have tablespace PSAPSR3740 then it would change as below
First SP update: PSAPSR3740 -> PSAPSr3740X
Second SP update PSAPSR3740X -> PSAPSR3740
Third SP update PSAPSR3740 -> PSAPSR3740X
.
.
and so on.
4. if your source release and target release are different then it would ask to create the tablespace with target release specific name but this would depend on correctness of your source system.
5. In any case you can correct the tablespace details after the upgrade with the help of your DBA. I think this point can be better explained by someone who have more knowledge about the database which you use.
Best Regards,
Gaurav