Basic System DMS PROC › SELECT Command › DSCL SELECT CRITERIA Field Name Descriptions › F1MODBIT — Format-1 DSCB modification (change) bit (on/off)

F1MODBIT — Format-1 DSCB modification (change) bit (on/off)

For non-VSAM data sets and VSAM components, the value of F1MODBIT is set to YES/TRUE/ON if the change bit DS1IND02 is set in DS1DSIND of the Format 1 DSCB for each data set or component. This differs from MODBIT for multi-volume data sets in that MODBIT is a composite setting that is set ON if any volume has the modbit set for that data set. F1MODBIT is not a composite setting and varies for each volume of a multi-volume data set.

The MODBIT selection criteria is valid for both SCAN REALVOLS and SCAN CAT but the F1MODBIT is valid only when using SCAN REALVOLS. The use of F1MODBIT may allow your CA Disk job to process more quickly, since it allows CA Disk to bypass some catalog processing.

For example, for HSM conversions to select only those multi-volume data sets having the modbit set on for volume sequence number 01 use:

SCAN REALVOLS
SELECT VOL=(SMD0/),

DSN=MULTIVOL.DATASET/,          
CRI=(VOLSEQNO,EQ,1,AND,F1MODBIT,EQ,ON)

Note: Certain applications bypass normal OPEN processing. Data sets updated by these applications will not have their change bits set. Thus, these data sets will never be selected by SEL CRI=(F1MODBIT,EQ,YES). To select all potentially modified data sets, you must specifically select these data sets.