UART WRITE -- max. size?

Hello,

I used UART to communicate anther chip. I used UART WRITE: void uart_write(uint8_t *bufptr, uint32_t size, void (*callback) (uint8_t)) for sending data out from DA14580.

Could you please let me know the max size for this function?

I used size=99, it works well, but when I use the size>100, the system didn't work. Please advise.

Thanks,
Alex