In a message dated 2/14/2008 11:06:10 A.M. Central Standard Time, [EMAIL PROTECTED] writes: >In 35+ years, I've never seen a directory block count stored anywhere; only the count of blocks used. The classic method of counting the total of directory blocks is to open the directory as a sequential dataset and read until EOF is encountered. I also have never seen the directory block count stored anywhere in a vani lla IBM system. Perhaps the poster was referring to a non-IBM use of some reserved field in the Format 1 DSCB. Also I have never heard of storing the count of blocks used anywhere. Where is this piece of data stored in vanilla IBM metadata? The Format 1 DSCB has a one-byte field for the number of bytes used in the last directory block and a 3-byte field for the TTR of the last used block in the entire data set. Perhaps you were thinking of one of those fields. The reason that a PDS directory entry that describes a load module is larger than a directory entry for other types of data is that load modules store info in the entry that is used by program fetch when the load module is being loaded. I don't remember the exact format of a directory entry, but there is at least one TTR stored in the entry as well as part of a byte telling how many halfwords of the directory entry are used for storing such data. Non-load modules have all these bytes containing zero. Some non-IBM products use this feature of a directory entry to store useful info, like date last used for the member. So non-load module entries will be larger than the mininum length (12 bytes, I think) if such software is installed and managing that PDS. There is a DSECT describing the directory entry somewhere in SYS1.MACLIB/MODGEN, I believe. Or maybe I saw this documented in a logic manual. Bill Fairchild Rocket Software
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