SQL Server : which role grants permission to execute all stored procedures? Which database role membership grants permission to execute all existing stored procedures in SQL Server 2012?

I tried adding a user to each of them and am still unable to execute a stored procedure. I don't want to grant EXECUTE for each stored procedure separately, I want to add the user to a role and he be able to execute any of them.
If you are using schemas other than the default dbo schema, create a database role per schema and grant EXECUTE on the schema to the role.

e.g.
For the default dbo schema:

CREATE ROLE role_exec_dbo
GO
GRANT EXECUTE ON SCHEMA::dbo to role_exec_dbo
GO


For a new schema:

CREATE SCHEMA mySchema
GO
CREATE ROLE role_exec_mySchema
GO
GRANT EXECUTE ON SCHEMA::mySchema to role_exec_mySchema
GO