Steps for examining address space dispatchability

Procedure

Enter IPCS SUMMARY FORMAT JOBNAME(xyz) to obtain a report for the hung job.

Locate the ASCB (F ASCB). For example:

ASCB: 00F2A280
   +0000  ASCB..... ASCB      FWDP..... 00F2A100  BWDP..... 00F2A400  LTCS..... 00000000  SVRB..... 009FD598  SYNC..... 000001DE
   +0018  IOSP..... 00000000  R01C..... 0000      WQID..... 0000      SAWQ..... 04CBAAF0  ASID..... 003D      R026..... 0000    
   +0028  LL5...... 00        HLHI..... 01        DPH...... 00EF      TCBE..... 00000000  LDA...... 7FF18EA0  RSMF..... C0      
   +0035  FLG3..... 00        R036..... 0000      CSCB..... 18E89D00  TSB...... 00000000  EJST..... 00000000  22CF88A0          
   +0048  EWST..... BEC51B1A  4660A320            JSTL..... 000141DE  ECB...... 809FDC80  UBET..... BE89F19D  TLCH..... 00000000
   +0060  DUMP..... 009FFE88  AFFN..... FFFF      RCTF..... 01        FLG1..... 00        TMCH..... 00000000  ASXB..... 009FDE88
   +0070  SWCT..... 00A7      DSP1..... 80        FLG2..... 00        RSV...... 0000      SRBS..... 000E      LLWQ..... 00000000
   +007C  RCTP..... 009FE0A8  LOCK..... 4FFFFFFF  LSWQ..... 04CBAAF1  QECB..... 00000000  MECB..... 40000000  OUCB..... 03292100
   +0094  OUXB..... 0384E6F8  FMCT..... 0000      LEVL..... 03        FL2A..... 80        R09C..... 00000000  IQEA..... 00000000
   +00A4  RTMC..... 00000000  MCC...... 00000000  JBNI..... 00000000  JBNS..... 00FAF60C  SRQ1..... 00        SRQ2..... 00      
   +00B6  SRQ3..... 00        SRQ4..... 00        VGTT..... 00000000  PCTT..... 00000000  SSRB..... 0000      SMCT..... 00      
   +00C3  SRBM..... 07        SWTL..... 00000D30  SRBT..... 00000001  301DBF80            LTCB..... 03748628  LTCN..... 00000005
   +00D8  TCBS..... 00000000  LSQT..... 00000000  WPRB..... 009FE950  NDP...... EF        TNDP..... FF        NTSG..... FF      
   +00E7  IODP..... FD        LOCI..... 00000000  CMLW..... 044AA6B8  CMLC..... 00000000  SSO1..... 000000    SSO4..... 00      
   +00F8  ASTE..... 03F05F40  LTOV..... 7FF95000  ATOV..... 7FFF0128  ETC...... 0001      ETCN..... 0001      LXR...... 0001    
   +010A  AXR...... 0000      STKH..... 009FE960  GQEL..... 19021900  LQEL..... 19021778  GSYN..... 00000000  XTCB..... 009F1598
   +0120  CS1...... C0        CS2...... 00        R122..... 0000      GXL...... 03105000  EATT..... 00000000  034077E0          
   +0130  INTS..... BE89F19D  91A9EA80            LL1...... 00        LL2...... 00        LL3...... 00        LL4...... 00      
   +013C  RCMS..... 00000000  IOSC..... 00000067  PKML..... 0000      XCNT..... 01F4      NSQA..... 00000000  ASM...... 03896540
   +0150  ASSB..... 03AA4280  TCME..... 00000000  GQIR..... 00000000  R15C..... 00000000  00000000  00000000  CREQ..... 00000000
   +016C  RSME..... 03807290  AVM1..... 00        AVM2..... 00        AGEN..... 0000      ARC...... 00000000  RSMA..... 03807128
   +017C  DCTI..... 0000062E

Check the following fields in the ASCB control block:
DSP1 (+X'72')
Address space non-dispatchability bits:
- If X'80', an SVC dump is in progress, which does not indicate a problem.
- If X'40', an address space is failing. Check field MCC (ASCB+X'A8') for the memory termination completion code (MCC=8840D000). If so, this job is terminating with an ABEND40D. Extract the associated reason code from field ARC (ASCB+X'174').
- If X'10' or X'32', the address space is logically or physically swapped out. To determine the reason for the swap, issue the IPCS VERBX SRMDATA and FIND the job name (F jobname).
LOCK (+X'80')
Address space local lock word:
- If the word contains X'7FFFFFFF', a TCB or SSRB is suspended holding the local lock. To locate the PSW and registers for the lock holder, enter FIND IHSA. Use the IPCS WHERE command on the address from CPSW (current PSW) in the IHSA to identify the lock holder. Use this module name in a search.
- If the word contains X'0000004X', this identifies that the lock holder is currently executing on CP 4x at the time of the dump. Do an IPCS SYSTRACE CPU(4x), go to the bottom of the output and scroll back examining the trace entries to see what unit of work is executing. For information on interpreting system trace, see system trace in z/OS MVS Diagnosis: Tools and Service Aids.
- If the word contains X'4FFFFFFFF' or X'FFFFFFFF' (the SRB or TCB ready to run id), then the unit of work is on the dispatching queue and waiting to get dispatched. Go to Steps for examining why a job is not running.