Testing to see if System is in Restricted Condition

Here's some code from our weekly backup program:
It ends all subsystems, then checks every minute until subsystems are ended.

pgm

/* API variables */
dcl var(&receiver) type(*char) len(100)
dcl var(&receiverl) type(*char) len(4) value(x'00000064')
dcl var(&format) type(*char) len(8) value('SSTS0200')
dcl var(&reset) type(*char) len(10) value('*YES')
dcl var(&error) type(*char) len(4)
dcl var(&rstdflag) type(*char) len(1)

/* .... */

/* End subsystems for save operation */
sndpgmmsg msgid(cpf9898) msgf(qcpfmsg) +
    msgdta('** Ending all subsystems immediately') tomsgq(*sysopr)
endsbs sbs(*all) option(*immed)

sbscheck:
call pgm(QWCRSSTS) parm(&receiver &receiverl &format &reset &error)
/* Restricted state flag is byte 31 (offset 30):          */
/* 0 = not in restricted state                            */
/* 1 = restricted state                                   */
chgvar var(&rstdflag) value(%sst(&receiver 31 1))
if cond(&rstdflag *eq '0') then(do)
    sndpgmmsg msgid(cpf9898) msgf(qcpfmsg) +
         msgdta('** Waiting for subsystems to end') tomsgq(*sysopr)
    dlyjob dly(60)
    goto cmdlbl(sbscheck)
enddo

/* In restricted state, can perform backup */
rste:

endpgm

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