SDTMEMLIMIT

The SDTMEMLIMIT system initialization parameter specifies a limit to the amount of storage above the bar that is available for shared data tables to use for control information (entry descriptors, backout elements, and index nodes). The default is 4 GB. When you set this system initialization parameter, check your current setting for the z/OS® MEMLIMIT parameter.

Defining SDTMEMLIMIT

You can define the SDTMEMLIMIT system initialization parameter in the following ways:

On the PARM parameter of the EXEC PGM=DFHSIP statement
In the SYSIN data set of the CICS® start up job stream
Through the system console
In the DFHSIT macro

Values for SDTMEMLIMIT

Important: You can specify an amount of storage in the range 1 through 524288 MB (512 GB), but this amount must not be greater than 40% of the z/OS MEMLIMIT value. MEMLIMIT limits the amount of 64-bit storage that the CICS address space can use. If you set SDTMEMLIMIT to a value greater than 40% of the MEMLIMIT value, message DFHFC0418 is issued and CICS terminates.

For information about the MEMLIMIT value for CICS and instructions to check the MEMLIMIT value that currently applies to the CICS region, see Estimating and checking MEMLIMIT. For information about the z/OS MEMLIMIT parameter, see Limiting the use of private memory objects in the z/OS MVS Programming: Extended Addressability Guide.

Valid values for the SDTMEMLIMIT system initialization parameter are as follows:

SDTMEMLIMIT={4G|nnnnnnM|nnnG}

Valid values are as follows:

4G: 4G is the default value for SIT-SDTMEMLIMIT. The default amount of storage above the bar that is available for shared data tables to use.
nnnnnnM: Specifies an amount of storage above the bar, in megabytes, that is available for shared data tables to use. It can have a value in the range 1 through 524288 MB.
nnnG: Specifies an amount of storage above the bar, in gigabytes, that is available for shared data tables to use. It can have a value in the range 1 through 512 GB.