Coupling facility structure attributes

The attributes defined by VTAM® describe the various coupling facility structure characteristics. For the structures used by VTAM and TCP/IP functions, VTAM supplies all attributes to MVS™ listed in Table 1 and Table 2 with the exception of the maximum list counts attribute. The list-set-entry count or list-set-element count attribute is used to determine the size specified in the policy.

When the structure size has been determined, the corresponding CFRM policy can be defined following the directions in z/OS MVS Setting Up a Sysplex. For the sysplex to recognize a structure, a CFRM policy must be defined and active. This definition indicates that the coupling facility will contain the named structure.

Access to the structure occurs when VTAM connects to a coupling facility structure.

Table 1. Structure attributes used to compute structure size
Attribute	Generic resources	Multinode persistent sessions	Sysplex Wide Security Associations	Sysplexports
Adjunct	Yes	Yes	Yes	Yes
List entry reference	Names	Keys	Keys	Keys
List element characteristic	2	0	0	0
List count	4	256 ¹	2048	1024
Number of lock entries	3	0	0	1024
Maximum number of data elements	16	255	255	32
Initial entry-to-element ratio ²	List entry portion – 50 Data object portion – 1	List entry portion – 1 Data object portion – 2	List entry portion – 1 Data object portion – 10	List entry portion – 1 Data object portion – 32
Maximum list set element count	N/A	See Determining the size of the coupling facility structure	N/A	N/A
Maximum list set entry count	See Determining the size of the coupling facility structure	N/A	See Determining the size of the coupling facility structure	See Determining the size of the coupling facility structure
Lock table entry characteristic	0	0	0	0
Notes: The list count number can increase across a structure rebuild. Issue DISPLAY STATS,TYPE=CFS to get the current number of lists allocated. During the rebuild process this ratio might be altered to better fit the actual use of list entries and elements. VTAM can also use the dynamic structure alter to change this ratio.

Table 2 contains structure attributes used to determine the coupling facility preference and exclusion list for a structure.

Table 2. Structure attributes defined by VTAM
Attribute	Generic resources	Multinode persistent sessions	Sysplex Wide Security Associations	Sysplexports
Structure type	List	List	List	List
Structure rebuilds allowed	Yes	Yes	Yes	Yes
Structure connection disposition	KEEP	KEEP	DELETE	DELETE
Structure disposition	DELETE	KEEP	DELETE	DELETE