Please check the following documents:
2) Interrupt section of CAN component datasheet: http://www.cypress.com/file/179861/download
3) In case you are using PSoC 4L device, refer to Message Transmit Process section 17.4.2 of Architecture TRM: http://www.cypress.com/file/218741/download.
Else, please refer to the respective device TRM's CAN section.
I hope this helps.