Request URI too large for inserRecords API

I m using insertRecords api to upload contacts from android to zoho crm server.

https://crm.zoho.com/crm/private/json/Contacts/insertRecords?authtoken=my_token&scope=crmapi&xmlData=encoded_data

The characters count from xmlData is near 12K. Server throws message as Request URI too large.
I've tried the same request in rest client and postman. Got the same error.
Should I limit the no of records for uploading? I did already as 100 records. Zoho CRM api doesn't support to send via post body. How to get rid of this?

Thanks for the help!