CICS facilities that use 64-bit storage

The CICS® facilities that use 64-bit storage and the amount of storage that each facility requires are listed. You can use this information when you estimate a suitable MEMLIMIT value for your CICS region.

The following table lists CICS facilities that use 64-bit storage and the relevant CICS storage subpools, and indicates the amount of storage that each facility requires. You can identify the facilities that you use in your CICS region that require 64-bit storage. You can then examine the storage requirement for those facilities and use this information to estimate a suitable value for the z/OS® MEMLIMIT parameter.

Table 1. CICS facilities that use 64-bit storage

CICS facility	Storage use	CICS subpool for storage	Notes
Application context data control blocks	220 bytes for each program that is defined as an application entry point.	PGPPTE64
Association data control blocks	Approximately 1 KB for each active task.	MN_ADCS
CICS management client interface (CMCI)	For the details to estimate storage requirements, see Estimating storage requirements for CMCI.	WU_64	The storage is used for retained results and metadata.
CICSPlex® SM API result sets	The size of the result set depends on the application.	CPSM_64	For information about result sets, see Working with result sets.
Console queue processing	1 MB per subpool	CQCQ_TR CQCQ_XT
Containers and channels	Limited to 5% of the MEMLIMIT value per transaction.	PGCSDB	The storage remains in use until an application deletes the container.
Event processing		EP_64	The storage is used for control blocks for items in event capture queues.
Internal trace table	Minimum 16 KB Maximum 1 GB Default 4096 KB Controlled by the TRTABSZ system initialization parameter.	MVS™ storage outside the CICS DSAs
JVM servers	Apart from the values in -Xmx and -Xcmsx, the amount of storage is variable.	MVS storage outside the CICS DSAs
Loader control blocks	Variable	LD_APES LD_CPES LD_CSECT	The storage used depends on the number of program load operations in the CICS region.
Loader control blocks for installed application elements (IAE)	368 bytes for each IAE	LD_IAES	Each installed application element represents a particular version of an application that is deployed on a platform.
Main temporary storage	Minimum 1 MB Maximum 32 GB Default 64 MB Controlled by the TSMAINLIMIT system initialization parameter.	TSDTN TSMAIN TSMN0064 TSMN0128 TSMN0192 TSMN0256 TSMN0320 TSMN0384 TSMN0448 TSMN0512 TSMN0576 TSMN0640 TSMN0704 TSMN0768 TSMN0832 TSMN0896 TSMN0960 TSMN1024 TSQUEUE TSTSI	TSMAINLIMIT specifies the maximum storage that can be used, and is limited to 25% of the MEMLIMIT value. The CICS statistics show actual use.
Managed Platform	896 bytes for each user task	DFHMPMDR DFHMPPMB DFHMPTAS	Storage in the DFHMPMDR and DFHMPPMB subpools is used for control blocks for installed policies. It remains in use until the bundle that defines the policy is disabled. Storage in the DFHMPTAS subpool contains the policy counters for a task. It is allocated for every user task if any polices are installed in the CICS region. The storage is freed at task end.
Message tables	Minimum 3 MB for the message modules in English. Add 1 MB if the user message table is loaded. Add 3 MB for each additional language that is loaded.	MVS storage outside the CICS DSAs	Message modules in English are always loaded.
Static data item control blocks	Variable	MPSTAT	Used if a policy rule with an event action defines static data capture items.
Storage allocation control blocks	Variable	MVS storage outside the CICS DSAs	Storage used depends on the amount of storage allocation activity in your system; for example, more storage is required for subpools that keep an element chain and that have many small records.
Transaction dump trace table	Minimum 16 KB Maximum 1 GB Default 1024 KB Controlled by the TRTRANSZ system initialization parameter.	MVS storage outside the CICS DSAs	CICS obtains this storage only when a transaction dump is produced.
z/OS XML System Services (XMLSS) parser I/O buffers		ML64GNRL	A number of facilities, including CICS web services, use the parser for XML parsing.