3710 (Insufficient memory to parse this request during Optimizer phase) on query with multiple full joins

Database

3710 (Insufficient memory to parse this request during Optimizer phase) on query with multiple full joins

There is a BI tool-generated SQL query which (full) joins multiple, 30 in total, smaller SQL as following:

(select a14.Store_ID Store_ID, sum(a11.CountConnections) WJXBFS1
from Retail_Views.F_ACM_Connections a11, ....
where filterset = 1) pa11

(select a14.Store_ID Store_ID, sum(a11.CountConnections) WJXBFS1
from Retail_Views.F_ACM_Connections a11, ....
where filterset = 2) pa12

....

into a query like:

select coalesce(pa11.Store_ID, ..., pa130.Store_ID) Store_ID, a132.StoreName StoreName, max(pa11.WJXBFS1) WJXBFS1, ..., max(pa130.WJXBFS1) WJXBFS30
from ....

The same query has been used for some weeks and executed OK but since yesterday both BI tool users and when SQL Assistant used get a "Failure: 3710 Error Insufficient memory to parse this request during Optimizer phase" error.

I've followed manual instructions and increased the value of MaxParseTreeSegs parameter from 1000 to 3000, but query still fails to get executed. Query is executed against a TD V2R5.1.

Any more ideas are welcome.