CEMT SET DSAS

Change the system storage attributes for dynamic storage areas (DSAs) below 16 MB and DSAs above 16 MB but below 2 GB. In CICS Explorer®, the Global Dynamic Storage Areas view is functionally equivalent to this command.

Input

  • Type CEMT SET DSAS (or suitable abbreviations for the keywords). The resulting display shows the status, similar to that obtained by using the CEMT INQUIRE DSAS command. You can tab to the highlighted or blank fields and over type them with the required values.
  • Type CEMT SET DSAS (or suitable abbreviations for the keywords), followed by one or more attribute settings that you want to change. For example, cemt s dsa ds(value) ed(value) resets the value for dynamic storage below 16 MB (below the line) and the value for dynamic storage above 16 MB but below 2 GB (above the line).

Typing ? at the beginning of either the first or second line gives a syntax prompt. Resetting the values takes effect immediately.

CEMT SET DSAS

Read syntax diagramSkip visual syntax diagramCEMT SET DSASDSALIMIT( value)EDSALIMIT( value)

Options

DSALIMIT(value)
Specifies the maximum amount of storage, as a total number of bytes, within which CICS® can dynamically allocate storage for the individual DSAs that reside below 16 MB. See DSALIM system initialization parameter. If DSALIMIT specifies a value that is lower than the current limit, CICS might not implement the new limit immediately, but attempts to do so over time as dynamic storage is freed in the individual DSAs.
EDSALIMIT(value)
Specifies the maximum amount of storage, as a total number of bytes, within which CICS can dynamically allocate storage for the individual DSAs that reside above 16 MB but below 2 GB (above the line). See EDSALIM system initialization parameter. If EDSALIMIT specifies a value lower than the current limit, CICS might not implement the new limit immediately, but attempts to do so over time as dynamic storage is freed in the individual DSAs.

For information about DSAs, see CICS dynamic storage areas (DSAs).

You can dynamically change the DSA and EDSA limits but it is not recommended, unless you are addressing an urgent situation and are trying to avoid cycling the region. Your change to the DSA and EDSA limits might be successful from the CICS perspective but increasing the limits can cause other problems because the larger DSA or EDSA is no longer contiguous. z/OS allocates storage both from the high private area growing down, and the low private area growing up. Increasing the DSA or EDSA limits dynamically causes a new piece of storage to be allocated by CICS in the middle of the MVS™ private storage area. As a result, depending on the use by z/OS of storage in this area, you can be at increased risk of an S878 or S80A abend. Similarly, decreasing the DSA or EDSA limits dynamically might indeed give back storage to z/OS for use but you cannot be certain where the storage is given back. It is most likely not in an area where z/OS needed it.

Monitor CICS statistics regularly and adjust DSA and EDSA limits and the limits of user tasks (with the MXT system initialization parameter).