This value specifies the size of the roll file in 8 KB blocks. The roll file functions as memory for the portion of the user contexts that finds space in the Roll Area.
The roll buffer is used to buffer accesses to the roll file. The buffer size is determined by the rdisp/ROLL_SHM parameter.
The default value is platform-specific and is determined dynamically. This is the default value specified in transaction RZ11. This value should not normally be changed.
Problems should not occur even if the buffer size is large.
Space must be available in the file system.