Error message 'sysparm_limit value must be a positive integer' is seen when making inbound REST API GET call with sysparm_limit=0
sysparm_limit is used to specify maximum number of records to be returned in the response. Setting it to 0 is considered invalid and this causes the request to fail.
If you are trying to retrieve less than 10,000 rows you can just remove the sysparm_limit from the query.
The system by default has a limit of 10,000. If the result is more than 10,000 the "x-total count" header in response contains the total number of records for the query.
You can use this and make as many calls needed to get all the records.
Note: The limit parameter defaults to 10,000 records. This limit can be set to any value. Be aware, however, that an unusually large value can impact system performance.
X-Total-Count Total count of records returned by the query.
The best practice to retrieve large number of records is by using pagination. You may follow the steps provided in KB0727636.