About SSL connection

ALTER SYSTEM SET configuration_parameter { TO | = } { value | 'value' | DEFAULT }

ALTER SYSTEM SET SSL = ON , querry executed successfully 

after that i entred this Select *  from pg_settings , i saw that ssl value is off,

after  stoping the service of postgresql it wont start again 

i tried this on both servers 11 and 10 the same problem (the server wont start again)

I'm using widonws 7 x64.

my question is  how to enbale SSL ?

ps : i created all require cert files.

sorry for my bad english.