tensorflow/core/ops/compat/ops_history_v1/Stack.pbtxt

op {
  name: "Stack"
  output_arg {
    name: "handle"
    type: DT_STRING
    is_ref: true
  }
  attr {
    name: "elem_type"
    type: "type"
  }
  attr {
    name: "stack_name"
    type: "string"
    default_value {
      s: ""
    }
  }
  is_stateful: true
}