CURRENT OF clause cannot refer to cursor based on prepared
  statement

  Explanation:  The CURRENT OF clause of an UPDATE or DELETE
  statement specifies a cursor based on a prepared statement.
  Because the prepared statements are generated at run time, you
  cannot precompile UPDATE or DELETE statements that refer to
  cursors based on them.

  User Action:  Use a cursor which is based on an embedded SELECT
  statement (which is known at compile time), or dynamically
  execute the UPDATE or DELETE statement so it can be interpreted
  at run time.