Singleton For DirContext For LDAP Configuration

I want to create a singleton for DirContext for LDAP configuration, hence i have used the initialize on demandclass holder idiom as shown below

public class SlmApplicationContext {
/**    
* inner class to hold the instance.    
*/   
private static class Holder {       
private static DirContext instance = new InitialDirContext();   
}
   
/**    
* Method to get the singleton instance of this class.    
* @return SlmApplicationContext    
*/   
public static SlmApplicationContext getInstance() {       
return Holder.instance;    }       
...       
}

Now the problem is if i close the DirContext.close(), when the next request comes the singleton wont    work as the dir context is already closed, hence it will create a new dir context for each requests. Which breaks the singleton concept, hence how we can ensure the  singleton works fine even with DirContext.close()?