CFLEVEL and operating system level coexistence

Table 1 shows which operating systems can use coupling facilities at different CFLEVELs, either to exploit the function provided by the CFLEVEL or to coexist with the CFLEVEL function without exploiting it. The area of the table with text (an X or an APAR number) is the “exploitation” area, showing operating system support of exploitation of the functions contained in a particular CFLEVEL. The blank area in the table is the “coexistence” area. This area indicates where an operating system can be used, but does not exploit the new functions contained in a particular CFLEVEL. For example, a system at z/OS® V1R4 can be used with a coupling facility at CFLEVEL 15, but can only exploit functions up to and including CFLEVEL 14.

If APARs are required for exploitation in addition to the operating system product code, the APAR number is shown in the corresponding CFLEVEL box. For example, to exploit CF functions in a coupling facility at CFLEVEL 15 on a z/OS V1R6 system, APAR OA17055 is required in addition to the V1R6 code.

Table 1. CFLEVEL Summary Table
Release	CFLEVEL
Release	10	11	12	13	14	15	16	17	18
z/OS V1R1
z/OS V1R2	X	OW53548 OW41617
z/OS V1R3	X	OW53548 OW41617
z/OS V1R4	X	X	X	OA01517	OA08742
z/OS V1R5	X	X	X	OA01517	OA08742
z/OS V1R6	X	X	X	X	OA08742	OA17055	OA25130
z/OS V1R7	X	X	X	X	X	OA17055	OA25130
z/OS V1R8	X	X	X	X	X	OA17055	OA25130
z/OS V1R9	X	X	X	X	X	X	OA25130
z/OS V1R10	X	X	X	X	X	X	OA25130	OA32807
z/OS V1R11	X	X	X	X	X	X	X	OA32807
z/OS V1R12	X	X	X	X	X	X	X	OA32807	OA38312 OA38734 OA40966
z/OS V1R13	X	X	X	X	X	X	X	X	OA38312 OA38734 OA40966
z/OS V2R1	X	X	X	X	X	X	X	Xo	OA40966

Note:

OA01517 is only required in order to enable CF exploiters who can benefit from the performance enhancements provided by CFLEVEL 13 to explicitly request structure allocation in a CFLEVEL 13 coupling facility. It is a "soft" prerequisite for use of a CFLEVEL 13 coupling facility. Installations that do not require the APAR to be applied can still install a CFLEVEL 13 coupling facility in their configuration and also can include its definition in the preference list in their CFRM policy. The system may allocate structures in the CFLEVEL 13 coupling facility without having the APAR applied to the system if the coupling facility meets all other CFRM criteria.
OA08742 is only required in order to enable CF exploiters who can benefit from the dispatching / latching enhancements provided by CFLEVEL 14 to explicitly request structure allocation in a CFLEVEL 14 coupling facility. It is a "soft" prerequisite for use of a CFLEVEL 14 coupling facility. Installations that do not require the APAR to be applied can still install a CFLEVEL 14 coupling facility in their configuration and also can include its definition in the preference list in their CFRM policy. The system may allocate structures in the CFLEVEL 14 coupling facility without having the APAR applied to the system if the coupling facility meets all other CFRM criteria.
There is significant growth in CFLEVEL 15 coupling facilities for the storage required for the CFCC code itself, the storage required for the individual structures that get allocated in the CF, and the storage increment size of the CF. See Washington Systems Center Flash 10572 for more detailed information about the amount of growth that can be expected for various types of CF structures.
When migrating to CFLEVEL 16, the CFCC storage increment size increases to 1M. Also the storage required for the individual structures might increase. This adjustment in structure size can have an impact when the system allocates structures or copy structures from one coupling facility to another with different CF levels.

The functions provided by each CFLEVEL are described briefly. For detailed information, see PR/SM™ Planning Guide.

0

Base coupling facility support

1

Structure alter support

2

New cache and lock structure functions for improved performance by allowing operations on lists of cache entries (batched registration) and lock entries (batched unlock), rather than on individual entries. These functions were intended for initial exploitation by DB2® and IRLM.

3

List monitoring enhancements for keyed list structures (“event monitoring”). The enhancements provide monitoring at a finer level of granularity than was available previously. These functions were intended for initial exploitation by IMS™ shared message queue.

4

Alter and dump support for list structures that use event monitoring.

5

User-managed duplexing of DB2 group buffer pools for added availability. This function was intended for initial exploitation by DB2.

6

Function provided for the TPF operating system. There is no new function for OS/390® exploitation, but all previous CFLEVEL function remains available.

7

Cache structure name class queue support that allows entries to be deleted more efficiently. This function was intended for initial exploitation by DB2.

8

System-managed rebuild support.

9

Support for list structure exploitation by MQ Series.

10

CF-to-CF connectivity support (required for CF Duplexing).

11

System-managed duplexing support for all coupling facility structure types.

12

Performance enhancements for cache structures by allowing batching of write requests, cross-invalidate requests, and castout requests. These functions were intended for initial exploitation by DB2.

13

Performance enhancements for cache structures for IXLCACHE REQUEST=READ_COCLASS requests. This function was intended for initial exploitation by DB2.

14

Coupling facility dispatching and latching performance enhancements.

15

Performance enhancements for CF duplexing to suppress RTE signals.

Note: This RTE suppression function is not enabled by z/OS.

Granular CF CP Utilization reporting by structure.

CF multitasking enhancements (increased number of CF tasks).

16

CF duplexing enhancements and shared message queue list notification enhancements.

17

CFCC non-disruptive coupling facility dumping support. Increased the maximum number of coupling facility structure instances per coupling facility image from 1023 to 2047 and provided support for greater than 32 connectors to a coupling facility list or lock structure. Installations should not deploy more than 32 instances of the application until the following recommendations are met.

Upgrade all relevant application instances to a level that supports greater than 32 connectors.
Ensure that the sysplex contains at least two coupling facilities that are CFLEVEL=17 or higher.

Failure to implement the recommendations stated above can result in an unsafe migration path to greater-than-32-connector support for a structure and can lead to failed connection attempts, failure to rebuild the structure, or failure to duplex the structure.

18

Functions include:

Cache performance and reliability improvements.
Coupling-related adapter interrupt exploitation.
Enhanced serviceability information for coupling channels.

The DISPLAY CF command will always display the actual CFLEVEL of the coupling facility. This may differ from what the application understands to be the operational level of the coupling facility. The operational level refers to the architectural level required to perform the necessary operations against the structure.