ThreadStatic is perfect for this.  A thread will be assigned to your
request, and the same thread will handle the whole request.  In an outer
scope you will need to establish the call context and save it into a
ThreadStatic variable.  Then call into whatever code you want to service
with the call context, and on return commit the transaction, and on any
exception, roll back.  Something like

class DBContext
{
 [ThreadStatic]
 public static DBContext CurrentContext;
 . . .

 public readonly SqlConnection Connection;
 . . .
}

. . .

DBContext.CurrentContext = new DBContext(...);
try
{
 //do whatever
 DBContext.CurrentContext.Commit();
}
catch (Exception ex)
{
 DBContext.CurrentContext.Rollback();
 throw ex;
}
finally
{
 DBContext.CurrentContext.Connection.Close();
 DBContext.CurrentContext = null;
}

Then anywhere in the call stack of the invoked components you can access the
CurrentContext's Connection with

 DBContext.CurrentContext.Connection

David