PURGE Macro Specification

The PURGE macro is used to halt or finish I/O requests.

Refer to “General-Use Mapping Macros” in z/OS MVS Programming: Authorized Assembler Services Reference ALE-DYN for information about using the 31-bit interface provided by the PURGE function.

The format of the PURGE macro is:


>>-+-------+--PURGE--parameter_list_address--------------------><
   '-label-'

parameter_list_address—RX-type address, (2-12) or (1): Address of a parameter list, 12 or 16 bytes long, that you have built on a word boundary in storage. The parameter list address can be specified as an RX-type address or in registers 2 through 12, or 1. The name of the mapping macro is IECDPPL.

The format and contents of the parameter list are as follows:

Byte

Contents

0

A byte that specifies the actions of the purge routines. The bit settings and their meanings are:

1... ....: Purge I/O requests to a single data set. The setting of this bit only takes effect if bit 2 of byte 12 is 0 and bit 6 of byte 0 is 0.
0... ....: Either purge I/O requests associated with a TCB or address space, or purge I/O requests to more than one data set. If bit 2 of byte 12 is 1, then the request is to purge I/O associated with an address space. If bit 2 of byte 12 is 0 and bit 6 of byte 0 is 1, then the request is to purge I/O associated with a TCB. If bit 2 of byte 12 is 0 and bit 6 of byte 0 is 0, then the request is to purge I/O to more than one data set.
.1.. ....: Post ECBs associated with purged I/O requests.
..1. ....: Halt I/O-request processing. (Quiesce I/O-request processing, if 0.)
...1 ....: Purge related requests. (Only valid if a data-set purge is requested.)
.... 0...: Reserved—must be zero.
.... .1..: Do not purge the TCB request-block chain of asynchronously scheduled processing.
.... ..1.: Purge I/O requests associated with a TCB. The setting of this bit will only take affect if bit 2 of byte 12 is 0.
.... ...1: This is a 16-byte parameter list. Additional purge options are specified in bytes 12 to 15. (If this bit is off, the list is 12 bytes long, and the purge routines do not put a return code in byte 4 of this list or in register 15.)

1,2,3

The address of a DEB when purging I/O requests to a single data set. The address of the first DEB in a chain of DEBs when purging I/O requests to more than one data set. (The next-to-the-last word of each DEB must point to the next DEB in the chain; the second word of the last DEB must contain zeros.)

4

A byte of zeros. (If bit 7 of byte 0 is on, the purge routines will put a code in byte: X'7F' when the purge operation is successful; X'40' when it is not successful. If bit 7 of byte 0 is off, then X'7F' appears in this byte.)

5,6,7

If you turned on bit 6 of byte 0, the address of the TCB associated with the I/O requests you want purged. Will be zeros if the TCB is the one you are running under.

8

Value of X'00' or X'02' means that EXCP is the owner.

9,10,11

The address of a word in storage or the address of the DEBUSPRG field (that is X'11' bytes more than the DEB address in this parameter list). At the address you specify, the purge routines store a pointer to the purged I/O restore list, that in turn contains a pointer to the first IOB in the chain of IOBs. The location of the pointer and format of the chain are shown in Figure 1.

Note: This field is only relevant for quiesce options.

12

A byte that allows you to specify additional purge options. The bit settings and their meanings are:

Note: The following applies only if bit 7 of byte 0 is set to 1.

..1. ....: Purge I/O requests associated with an address space. (Your program must be in supervisor state.) The setting of this bit will take affect regardless of the setting of bit 6 of byte 0 and bit 0 of byte 0.
...1 ....: If this is a data-set purge, check the validity of all the DEBs associated with the purge operation. Validate this parameter list, whatever the type of purge operation, by ensuring that there are no inconsistencies in the selection of purge options. (If your program is in problem state, these actions are taken regardless of the bit setting.)
.... 1...: Ensure that I/O requests will be reprocessed (restored) under their original TCB. (If zero, and bit 7 of byte 0 is on, the I/O requests are reprocessed under the TCB of the program making the restore request.)
.... .0..: Must be zero.

13

A byte of zeros.

14,15

If bit 2 of byte 12 is on, the 2-byte ID of the address space associated with the I/O requests you want purged.

Control is returned to your program at the instruction following the PURGE macro instruction.