apart the record layout and some missing information from the TS
I would rather go with something along the lines of
000005 //ICE EXEC PGM=SORT
000006 //SYSPRINT DD SYSOUT=*
000007 //SYSOUT DD SYSOUT=*
000008 //SORTIN DD *
000009 AS EMP1 HEADER
000010 JR 1 EMP1
000011 JR 2 EMP1
000012 JR 3 EMP1
000013 AS EMP0 HEADER
000014 JR 3 EMP0
000015 JR 4 EMP0
000016 JR 1 EMP0
000017 JR 2 EMP0
000018 AS EMP5 HEADER
000019 JR 1 EMP5
000020 JR 2 EMP5
000021 JR 3 EMP5
000022 JR 4 EMP5
000023 AS EMP2 HEADER
000024 JR 1 EMP2
000025 JR 2 EMP2
000026 JR 3 EMP2
000027 JR 4 EMP2
000028 //SORTOUT DD SYSOUT=*,
000029 // DCB=(RECFM=FB,LRECL=80)
000030 //SYSIN DD *
000031 SORT FIELDS=(51,4,CH,A,61,4,ZD,A)
000032 INREC IFTHEN=(WHEN=GROUP,BEGIN=(1,2,CH,EQ,C'AS'),
000033 PUSH=(51:4,4,61:SEQ=4))
which gives as output
********************************* TOP OF DATA **********************************
AS EMP0 HEADER EMP0 0001
JR 3 EMP0 EMP0 0002
JR 4 EMP0 EMP0 0003
JR 1 EMP0 EMP0 0004
JR 2 EMP0 EMP0 0005
AS EMP1 HEADER EMP1 0001
JR 1 EMP1 EMP1 0002
JR 2 EMP1 EMP1 0003
JR 3 EMP1 EMP1 0004
AS EMP2 HEADER EMP2 0001
JR 1 EMP2 EMP2 0002
JR 2 EMP2 EMP2 0003
JR 3 EMP2 EMP2 0004
JR 4 EMP2 EMP2 0005
AS EMP5 HEADER EMP5 0001
JR 1 EMP5 EMP5 0002
JR 2 EMP5 EMP5 0003
JR 3 EMP5 EMP5 0004
JR 4 EMP5 EMP5 0005
******************************** BOTTOM OF DATA ********************************
I did not cleanup the record to show the <auxiliary> sort fields