Like, from which memory point it starts executing??
Intial registers/pointers values?
When will the actual program starts executing from the first line?
One of the best guides to this came from Motorola, in their literature to a (moderately) old microcontroller.
I'd suggest reading this (pdf) book "Understanding Small Microcontrollers" from cover to page 216.
Although the book refers to an old microcontroller, the information is still relevant to most microcontrollers today.