The Post SVC (SVC 2) is simply a front end that calls the Branch Entry Post Routine and then exits.

000000                               12 S002POST CSECT ,
000000 18CF                          13          LR    R12,R15            ESTABLISH
                            00000    14          USING S002POST,R12                BASE REGISTER
                                     15 *
                            00000    16          USING @TCB,R4
                            00000    17          USING @RB,R5
                                     18 *
                                     19          @CALL POST               CALL POST BRANCH ENTRY
000002 58F0 0014      00014          20+         L     R15,20             MVT ADDRESS
000006 58F0 F028      00028          21+         L     R15,MVTPOST-@MVT(,R15) ROUTINE ADDRESS
00000A 05EF                          22+         BALR  R14,R15
                                     23 *
00000C 58F0 0014      00014          25          L     R15,20              MVT ADDRESS
000010 58F0 F024      00024          26          L     R15,MVTEXIT-@MVT(,R15)   EXIT ROUTINE
000014 07FF                          27          BR    R15

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