Allow users to do anything within his own schema but cannot create or drop the schema itself

Question

I have created a schema in SQL Azure using following permissions on my database role:

CREATE ROLE myrole AUTHORIZATION dbo;
EXEC sp_addrolemember 'myrole', 'myuser';

CREATE SCHEMA myschema AUTHORIZATION dbo;

GRANT ALTER, CONTROL, DELETE, EXECUTE, INSERT, REFERENCES, SELECT, UPDATE, VIEW DEFINITION ON SCHEMA::myschema TO myrole;

GRANT CREATE TABLE, CREATE PROCEDURE, CREATE FUNCTION, CREATE VIEW TO myrole;

Through the above defined permissions a user can create/drop his own schema, so to overcome the problem I tried the ALTER ANY SCHEMA permission. But this permission also denies the user to create/drop tables. What permissions are required in order to allow the user to do anything within his own schema but cannot create or drop the schema itself?