DSA size limits

It is not advisable to set the size of individual dynamic storage areas (DSAs), and usually it is not necessary. However, it is possible to set the size of some DSAs by using the CDSASZE, UDSASZE, RDSASZE, ECDSASZE, EUDSASZE, ESDSASZE, and ERDSASZE system initialization parameters.

For example, CDSASZE sets the size of the CICS® dynamic storage area (CDSA), and ECDSASZE specifies the size of the extended CICS dynamic storage area (ECDSA). The default value for these parameters is 0, indicating that the size of the DSA can change dynamically. If you specify a nonzero value, the DSA size is fixed.

If you specify DSA size values that in combination do not allow sufficient space for the remaining DSAs, CICS fails to initialize.
  • The limit on the storage available for the DSAs in 24-bit storage (below 16 MB) is specified by the DSALIM system initialization parameter. You must allow at least 256K for each DSA in 24-bit storage for which you have not set a size.
  • The limit on the storage available for the DSAs in 31-bit storage (above 16 MB but below 2 GB) is specified by the EDSALIM system initialization parameter. You must allow at least 1 MB for each DSA in 31-bit storage for which you have not set a size.

You cannot set the size of individual DSAs in 64-bit storage; that is, in the above-the-bar DSA (GDSA).