Use the following DFSORT JCL which will give you the desired results. I assumed that your input has RECFM=FB and LRECL=302. If you have different lrecl then make sure that you change M1F1CNTL to reflect the end position+1 where I am normalizing the free format key. Also change the positions in CTL2CNTL for JOINKEYS for F1.
Please get rid off the DCB parameters in your JCL as DFSORT can automatically calculate them for you.
//STEP0100 EXEC PGM=ICETOOL
//TOOLMSG DD SYSOUT=*
//DFSMSG DD SYSOUT=*
//IN DD DISP=SHR,DSN=Your Input FB 302 Byte file
//T1 DD DSN=&&T1,DISP=(,PASS),SPACE=(CYL,(X,Y),RLSE)
//OUT DD SYSOUT=*
//TOOLIN DD *
SELECT FROM(IN) TO(T1) ON(1,11,UFF) USING(CTL1) ALLDUPS
COPY JKFROM TO(OUT) USING(CTL2)
//*
//CTL1CNTL DD *
OPTION DYNALLOC=(SYSALLDA,50)
INREC BUILD=(003,11, $ KEY
198,35, $ FNAME
293,10) $ DOB
SORT FIELDS=(01,11,UFF,A,
12,35,CH,A,
47,10,CH,A)
SUM FIELDS=NONE
OUTFIL FNAMES=T1,
IFTHEN=(WHEN=GROUP,KEYBEGIN=(1,11),PUSH=(58:12,45))
//*
//CTL2CNTL DD *
OPTION DYNALLOC=(SYSALLDA,50)
JOINKEYS F1=IN,FIELDS=(303,11,A),TASKID=M1
JOINKEYS F2=T1,FIELDS=(001,11,A),SORTED,NOSEQCK,TASKID=M1
REFORMAT FIELDS=(F1:1,302)
//*
//M1F1CNTL DD *
INREC OVERLAY=(303:3,11,UFF,M11,LENGTH=11)
//*
//M1F2CNTL DD *
OMIT COND=((12,45,CH,EQ,58,45,CH),OR,
((12,35,CH,EQ,58,35,CH),AND,(47,10,CH,NE,93,10,CH)),OR,
((12,35,CH,NE,58,35,CH),AND,(47,10,CH,EQ,93,10,CH)))
INREC BUILD=(1,11,UFF,M11,LENGTH=11)
//*