Associating latch contention with a logger TCB or WEB

If the logger address space hangs, it might be useful to investigate what latches logger holds. To find out what local latches are being used by system logger, you can either use the D GRS, C command from an MVS™ console or use the IPCS command IP ANALYZE RESOURCE to format the information in a dump. A sample of a logger latch is as follows:

SYS.IXGLOGER_LCBIT_CTA:00000257_SLSA:0001 ASID=0016 Latch#=11

The CTA number identifies which structure task (IXGWITSK) holds the latch and the ASID identifies the logger (IXGLOGR) address space. The latch number indicates the type of log stream latch that is held.

To find out what processing occurred under the unit of work, follow these steps:

Use the IP ANALYZE RESOURCE command to determine the WEB and TCB addresses. The command will generate output as shown in Figure 1.
Figure 1. Example: Output from IP ANALYZE RESOURCE command
```
RESOURCE #0018: NAME=SYS.IXGLOGER_LCBIT_CTA:00000257_SLSA:0001 ASID=0016 Latch#=11

RESOURCE #0018 IS HELD BY:
  JOBNAME=IXGLOGR   ASID=0016  WEB=029E4598
   DATA=SHARED  RETADDR=86102ABE
   REQID=0000005800000001

RESOURCE #0018 IS REQUIRED BY:
  JOBNAME=IXGLOGR   ASID=0016  TCB=007EB6B8
   DATA=EXCLUSIVE  RETADDR=860BAFC6

  JOBNAME=IXGLOGR   ASID=0016  TCB=007F91C8
   DATA=EXCLUSIVE  RETADDR=860A70A2
```
Note:
1. The RETADDR identifies the latch requestor.
2. The WEB address can be located in an SSRB in the IXGLOGR address space.
3. The TCB address will match the PTCB in an SSRB in the IXGLOGR address space.
4. The REQID will match the STOKEN of an RQE.

Issue the following command to find the associated SSRB by searching for the WEB or PTCB address (note the linkage stack pointer (LSDP) at +C0).

IP SUMMARY FORMAT REGS JOBNAME(IXGLOGR)

Figure 2 is a sample of the output from this command.

Figure 2. Example: Output from IP SUMMARY FORMAT command

LOCAL SUSPENDED SRB QUEUE
SSRB: 030DA988

   +0000  ID....... SSRB      FLNK..... 0341D310    ASCB..... 00FA3280
   +000C  CPAF..... 0000      PASI..... 0016        PTCB..... 007EB6B8
   +0014  EPA...... 00000000  RMTR..... 813C4C60    PARM..... 00000000
   +0020  WEB...... 029E4598  PKF...... 00          FLGS..... 08
   +0026  HLHI..... 00        FLGS..... 00          FRRA..... 00000000
   +0030  FPRS..... 00000000  00000000   00000000   00000000  00000000
   +0044            00000000  00000000   00000000   TRAN..... 00000000
   +0054  SAFN..... 0000      TYPE..... 0C          FLGS..... F8
   +0058  GPR0..... 00000000  GPR1..... FFFFFFFF
   +0060  GPR2..... FFFFFFFF  GPR3..... FFFFFFFF      GPR4..... FFFFFFFF
   +006C  GPR5..... FFFFFFFF  GPR6..... FFFFFFFF      GPR7..... FFFFFFFF
   +0078  GPR8..... FFFFFFFF  GPR9..... FFFFFFFF      GPRA..... FFFFFFFF
   +0084  GPRB..... FFFFFFFF  GPRC..... FFFFFFFF      GPRD..... FFFFFFFF
   +0090  GPRE..... FFFFFFFF  GPRF..... 86148DEC
   +0098  CPSW..... 470C0000  8112F9A2
   +00A0  CPUT..... 00FFFFFF  E0403800
   +00A8  TIME..... 00000000  0B242800                XSB...... 030DAF80
   +00B4  ORMT..... 06150B10  LSA1..... 023B5048      R0BC..... 00060110
   +00C0  LSDP..... 023B5168  ALOV..... 00000000

After locating the SSRB (suspended SRB) in the logger address space using the WEB or TCB address, use the following commands to format the linkage stack entries (LSE) and identify what processing occurred under that SRB by using the LSDP pointer from the SSRB.

IP List LSDP-A0
IP EQ LSE1 X
IP CBF LSE1 STR(LSE)

LSE: 023B50C8
   GENERAL PURPOSE REGISTER VALUES
   00-03.... 25D663D4  266F1B30  00000000  266F1728
   04-07.... 00FE8AC8  00000C58  00000000  00FCD080
   08-11.... 25F59A50  266F0018  266F1B30  06148D9F
   12-15.... 06147DA0  266F1950  00000317  00020000            <--IXGL1WRK
   PKM...... 8000      SASN..... 0016      EAX...... 0000
   PASN..... 0016      PSW...... 470C0000  86148DEC
   TARG..... 00000317  MSTA..... 00000000  00000000
   TYPE..... 05
       PC STATE ENTRY
   RFS...... 02A0      NES...... 0000