How to configure connection autocommit=false?

[Max Bogdanov]

Hello,
I am using Resin AS (4.18), MSSQL Server(2005) and Hibernate as JPA provider. How to configure connection autocommit=false? By default it's true.
Datasource configuration from resin.xml:

<database>
	<jndi-name>jdbc/myDB</jndi-name>
	<driver type="com.microsoft.sqlserver.jdbc.SQLServerDriver">
		<url>jdbc:sqlserver://MY_DSN:1210;databaseName=myDB;</url>
			<user>user</user>
			<password>pass</password>
	</driver>
	<prepared-statement-cache-size>8</prepared-statement-cache-size>
	<max-connections>20</max-connections>
	<max-idle-time>30s</max-idle-time>
</database>

Test code from a servlet:

private void doStuff() {
        try {
            Context env = (Context) new InitialContext().lookup("java:comp/env");
            DataSource pool = (DataSource) env.lookup("jdbc/myDB");
            Connection conn = pool.getConnection();
            try {
                logger.warning(String.format("autocommit=%s", Boolean.toString(conn.getAutoCommit())));
            }finally{
                conn.close();
            }
        } catch (SQLException ex) {
            Logger.getLogger(TestServlet.class.getName()).log(Level.SEVERE, null, ex);
        } catch (NamingException ex) {
            Logger.getLogger(TestServlet.class.getName()).log(Level.SEVERE, null, ex);
        }
    }

Output:
[12-09-10 13:04:01.516] [WARNING] [com.jp.web.TestServlet] [#22] > autocommit=true

As a result I cannot use transactions in my application, then I try to rollback the transaction I receive exception:
...
Caused by: com.microsoft.sqlserver.jdbc.SQLServerException: Cannot invoke a rollback operation when the AutoCommit mode is set to "true".
...

I can't use conn.setAutoCommit(false); method directly as I use hibernate as JPA provider.

Thanks.