The NoteBook of EricKong

  BlogJava :: 首页 :: 联系 :: 聚合  :: 管理
  611 Posts :: 1 Stories :: 190 Comments :: 0 Trackbacks
A sequential PS File doesn’t have any partitions or members(0 members). So, it doesn’t have a directory to look upto. Thus, the space allocated to a directory, in terms of Directory Blocks for a Sequential PS File is 0.

On the other hand, for Partitioned Dataset(PDS), it can contain 1 or more members. So, it needs a directory to record the whereabouts(location) of its members, which are scattered throughout the memory randomly. You need to allocate space in terms of Directory Blocks to a Directory in Partitioned Dataset(PDS). Thus, Directory Blocks for a PDS should be some finite number, say 5 blocks, or 10 blocks.

Suppose you are creating a new File AGY0157.EMPLOYEE.DATA. You specify the Directory Blocks on the ISPF Menu 3.2 screen, as follows -

1. If you want the file AGY0157.EMPLOYEE.DATA to be a Physical Sequential File(PS), then fill the Directory Blocks field = 0.

Image85[1]

2. On the other hand, if you want the file AGY0157.EMPLOYEE.DATA to be a Partitioned Dataset(PDS), having 1 or many members, and a directory, specify Directory Blocks field = 1,2,3 or ...(any finite value) blocks. In the figure below, I have put Directory Blocks = 5 Blocks.


Image86[1]
posted on 2011-12-20 17:26 Eric_jiang 阅读(211) 评论(0)  编辑  收藏 所属分类: Mainframe