stackPolicyUrl

Location of a file that contains the stack policy. The URL must point to a policy (maximum size: 16 KB) located in an Amazon S3 bucket in the same Amazon Web Services Region as the stack. The location for an Amazon S3 bucket must start with https://. URLs from S3 static websites are not supported.

You can specify either the StackPolicyBody or the StackPolicyURL parameter, but not both.