Thank you for your answer Chris.
I remembered I had seen this type of sentence in a doc
tries you make in the Add a Service dialog are appended to the SERVICE_NAMES parameter entry which has a 4KB limit. Therefore, the total length of the names of all services assigned to an instance cannot exceed 4KB.
After your answer, i searched and i found it :
http://docs.oracle.com/cd/B14117_01/rac.101/b10765/hafeats.htm Thank you
February 11, 2016 - 3:12 am UTC
(Untested) but if memory serves, in later releases (11.2 maybe?) then when you are using Grid control, the service_names parameter was not the sole aribiter of services - it was controlled up in the clusterware, so the 4k limit was not a drama.
If you are not using Grid control, and just using DBMS_SERVICE then perhaps the same limit might still apply.
I stress - dont take this as gospel. These are just my idle musings.
Cheers,
Connor