DSALIM

The DSALIM system initialization parameter specifies the higher limit of the total amount of storage within which CICS® can allocate the individual dynamic storage areas (DSAs) that reside in a 24-bit storage.

From the storage that you specify by using the DSALIM system initialization parameter, CICS allocates the dynamic storage areas that reside in a 24-bit storage. For information about CICS dynamic storage areas, see CICS dynamic storage areas (DSAs).

If your installation is constrained for a 24-bit storage, set a value for the DSALIM system initialization parameter equivalent to the sum of the 24-bit DSAs. If you have sufficient virtual storage to allow a greater value for the DSALIM system initialization parameter, see Estimating, checking, and setting DSALIM for considerations. The maximum value that you can specify for the DSALIM system initialization parameter is limited by the following factors:
  • The configuration of your MVS storage, which governs how much private storage remains beneath the line.
  • The size that you specified for the CICS region on the z/OS® REGION parameter in the CICS job or procedure. The DSALIM system initialization parameter value must be smaller than the REGION size specified for the CICS job, or smaller than the limit specified in the IEFUSI exit.
  • The amount of MVS storage, outside the DSAs, that you require to satisfy z/OS GETMAIN requests for a 24-bit storage.

If you change the DSALIM system initialization parameter value while CICS is running, the change is cataloged in the local catalog. If the DSALIM system initialization parameter is specified in the system initialization table, the cataloged value that is specified by the change overrides the value of the DSALIM system initialization parameter on an initial, cold, or warm start. The cataloged value is not used if you specify DSALIM as a system initialization parameter override (for example, in SYSIN), or if you reinitialize the CICS catalog data sets.

To control the equivalent limit for extended dynamic storage areas, see EDSALIM system initialization parameter.

Defining DSALIM

You can define the DSALIM system initialization parameter in the following ways:
  • In the PARM parameter of the EXEC PGM=DFHSIP statement.
  • In the SYSIN data set of the CICS startup job stream.
  • Through the system console.
  • In the DFHSIT macro.

Values for DSALIM

DSALIM={5M|number}
Valid values for the DSALIM system initialization parameter are as follows:
5M
5M is the default value for DSALIM.
number
A value in the range 2 MB to 16 MB, in multiples of 256 KB. If the size specified is not a multiple of 256 KB, CICS rounds the value up to the next multiple. You can specify number as a number of bytes, a whole number of kilobytes, or a whole number of megabytes. Use the letter M to indicate that the value represents a whole number of megabytes (for example, 4 M). Use the letter K to indicate that the value represents a whole number of kilobytes (for example, 4096 K), in which case the number is rounded up to the number of megabytes. If transaction isolation is active, the extent size for the user DSA is 1 MB and each user DSA extent must be aligned on a megabyte boundary. Otherwise, the allocation is in 256 KB extents for all the 24-bit DSAs.