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Categories of Data Description Parameters z/OS MVS IPCS User's Guide SA23-1384-00 |
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Data description parameters fall into five categories:
The address and length parameters specify the location and size
of the data item. The following are all valid addresses or address
expressions:
Two typical uses of the full range of data display parameters are
the EQUATE and LIST subcommands. For example, the following subcommand
creates a symbol table entry for the symbol ABC:
The symbol is associated with an 80-byte area beginning at X'A72F4'. ASID indicates that this address is virtual and IPCS simulates dynamic address translation for ASID(1). The AREA, SCALAR, and REMARK parameters specify information about this area that you want for future reference. AREA indicates that it is neither a module nor a control block. SCALAR indicates it is a single block of storage, not an array. The REMARK is your description of the 80-byte area. Having created the symbol, you can now display its storage with
the LIST subcommand. For example, the following subcommand displays
the 80-byte buffer:
To display that storage without first defining the symbol, enter:
This subcommand displays the same data (except the remark), in the same format, as the previous example. Note that the length is defined in hexadecimal. If you want to see the 20-byte field following the buffer and you
want it displayed in character format, enter:
Another way to accomplish the same thing is to enter:
This example sets X, the current address, to the end of the buffer and specifies a length of X‘14’. The LIST subcommand then displays this area in character format. Suppose you have located a segment table at X‘7FFFD000’. If you
want to display entries for segments six through ten, enter:
This displays the five segment table entries beginning at X‘5A2418’ (each segment table entry is four bytes). The total length of the five entries is 20 bytes. To list the contents of the general-purpose registers as they were
at the time of the dump, enter:
This displays all 16 general-purpose registers at your terminal. To display the four floating-point double precision registers in
hexadecimal, specify:
Note that when a symbol is assigned an offset, the offset is stored
separately and is not added to the base address. Thus, the following
subcommand creates a symbol record called A representing an address
of 1000 and an offset of 10:
In a similar manner, the following subcommand uses only the address portion
of A (1000) and creates a symbol, B, with an address of 1000 and an
offset of 20:
This design is used for the concept of fields within control blocks. Each field is considered at an offset from the beginning of the control block, not at an offset from another field. |
Copyright IBM Corporation 1990, 2014
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