making use of the directive "using X" reduces PUSHes & POPs in final SRC to :

RSEG  ?PR?ext_int_0?PS2_INTERR_C_ASM
    USING	1
ext_int_0:
    PUSH 	ACC
    PUSH 	B
    PUSH 	DPH
    PUSH 	DPL
    PUSH 	PSW
    USING	1
    MOV  	PSW,#08H
    .
    .
    .
 

It is used in C as:

void ext_int_0(void) interrupt 0 using 1 //external interrupt 0, reg. bank 1
{
    .
    .
    .
}
 

Thanks everyone.