PBP uses the hardware Stack. But with 31 levels on the 18F's, you have to be pretty sloppy to overflow it.

The PIC itself uses the Hardware Stack to handle an interrupt. But, DT_INTS does NOT use the Hardware Stack. It essentially uses a 2-level software stack. 1 for High Priority, and 1 for Low.

Once in an interrupt, it's OK to call a subroutine, as long as both HIGH and LOW priorities can never call the same routine at the same time.

HTH,