You can export the availability fields with the custom export field selector.
Here are the steps:
1- Select the products and go to Export>Custom
2- Select the fields from the Availability section.
3- Download the file from the “Notifications” from the top right.
These are the fields in the file.
IMPORTANT NOTE: To send force_stock_status as null, type “None or none”. To set, use one of the available values (in_stock_1 etc.)
IMPORTANT NOTE: To set “is_discontinued” and “orderable” ,type “Yes or yes”. To close, type “No or no”.
4- After the changes, upload the file back into SA.