Specifying the return area for IFCID 0306 requests

You must specify the return area for IFCID 0306 requests.

About this task

Begin program-specific programming interface information.The return area for monitor programs that issue IFCID 0306 requests must reside either in ECSA key 7 storage or in the 64-bit common key 7 storage area above the 2-GB bar. The IFCARA64 processing flag in the IFCA controls the location of the return area. If the return area resides in 64-bit common storage, the first eight bytes of the ECSA key 7 return area must contain a pointer to the location of the return area in the 64-bit common storage.

The IFI application program must set the eye-catcher to 'I306' at offset 4 in the return area before making the IFCID 0306 call. An additional 60-byte area must be included after the 4-byte length indicator and the 'I306' eye-catcher. This area is used by Db2 between successive application calls and must not be modified by the application.

The IFI application program must run in supervisor state to request the key 7 return area. The storage size of the return area must be a minimum of the largest Db2 log record returned plus the additional area defined in DSNDQW04. Minimize the number of IFI calls required to get all log data but do not over use ECSA by the IFI program. The other IFI storage areas can remain in user storage key 8. The IFI application must be in supervisor state and key 0 when making IFCID 0306 calls.

Important: The recommended size of the ECSA return area for IFCID 306 requests is between 66 KB and 200 KB. Specifying more than 200 KB for this return area might cause performance problems or even failures for other critical application programs that depend on ECSA storage. Because the log record counter is a 2 byte value, IFCID 306 might also return an incorrect count of log records if too much space is specified for the ECSA return area.

IFCID 0306 has a unique return area format. The first section is mapped by QW0306OF instead of the write header DSNDQWIN. End program-specific programming interface information.