The prologue of the procedure , the prologue of the function - part of the machine code at the beginning of the procedure (function), which prepares the stack and machine registers - saves the execution context - for further use in the body of the procedure (function).
Accordingly, the epilogue of a procedure ( function ) is part of the machine code at the end of the procedure (function), restoring the stack and machine registers to the state preceding the call of this procedure (function).
The prologue and epilogue are not part of the programming language, but are used by compilers ( assemblers ) as an agreement and, usually, have a single form for all procedures of this compiler implementation.