Obtaining CSM dumping information

To debug problems associated with the application's use of CSM buffers, it might be necessary to include CSM storage in a dump.

In order to include CSM storage in a dump, an application can use the following information:

Dumping area containing CSM data structures, pool structures, and buffer headers:
- Location extended common service area (ECSA)
- Subpool 241
- Key 6
These areas can be included in a user dump by specifying the subpool and key on the invocation of the SDUMPX macroinstruction.
Dumping buffers in an ECSA buffer pool:
- Location Extended CSA (ECSA)
- Subpools 231
- Key 6
The ECSA buffer pool can be included in a user dump by specifying the subpool and key on the invocation of the SDUMPX macroinstruction.
Dumping buffers in a data space buffer pool:
- Location common area data space (CADS) owned by the master address space
- Key 6
- Data space address range 4 KB - 2 GB
- Data space STOKENs and ALETs provided by IVTCSM REQUEST=DUMP_INFO.

Guideline: Applications should include the areas containing CSM data structures by specifying the subpools and key to reduce the amount of data included in the dump. Selective dumping is most important when dumping data in a CSM data space rather than dumping the entire 2 Gigabyte contents.

For ease of dumping CSM buffers during testing, an application can use ECSA buffers because this area can be included in a dump using the subpool and key. After the application is debugged, data space buffers can be used for the production application.

An application can request the location of information required to obtain CSM data space information in a dump on the following macroinstructions:

The application can perform the following actions:

Specify the address of an area on the DS_INFO parameter where CSM places the address of the area containing the CSM data space information. This information is mapped by the IVTDATSP DSECT. See CSM data space information (IVTDATSP).
Request the information during initialization processing and use the information throughout normal processing.

Dumping the entire data space can require a long processing time and a large amount of external recording media. Because of this, you might want to limit the amount of area dumped based on address ranges within the data space believed to be pertinent to the user. For example, use the ALETs returned by the IVTCSM REQUEST=DUMP_INFO macroinstruction to determine whether, at the time of abend, any access registers (AR) contain an ALET associated with a CSM data space. If an AR contains an ALET of a CSM data space, and the program was executing in AR mode at the time of the failure, you can dump a limited number of bytes of the data surrounding the address represented by the general register (GR) and AR pair.