BUFLIST and Its Associated Parameters

BUFLIST

The BUFLIST parameter specifies the address of a storage area (the buffer list) that contains the addresses of up to 16 buffers. These buffers do not have to be contiguous, however, the system treats them as if they form a single buffer. Data is transferred to or from the set of buffers in order of ascending buffer number. The buffer list, shown in Figure 1 and Figure 2, has the following characteristics:

The buffer list consists of a 128-byte storage area containing a list of 0 to 16 buffer addresses.
Each entry in the buffer list consists of an 8-byte field in which either the high-order (left-most) 4 bytes are reserved and the low-order (right-most) 4 bytes contain the address of a buffer or the entire 8 bytes contain the address of a buffer.
Note: Only the number of buffer list entries that you specify with the BUFNUM parameter must be formatted in this manner. For instance, if you specify a BUFNUM value of 5, all buffers beyond the fifth are ignored.

Figure 1. Format of Buffer List Specified by the BUFLIST Parameter

Figure 2. Format of Buffer List - 64-bit Addresses

All buffers in the buffer list must be the same size. Other requirements depend on the request:

For READ, WRITE, MOVE, DELETE, and MONITOR_SUBLISTS requests, the buffers must:
- Be 256, 512, 1024, 2048, or 4096 bytes
- Start on a 256-byte boundary
- Not cross a 4096-byte boundary
- Not start below storage address 512
For DELETE_ENTRYLIST, READ_LIST, READ_MULT, DEQ_EVENTQ, and READ_LCONTROLS requests, the buffers must:
- Be 4096 bytes
- Start on a 4096-byte boundary
- Not start below storage address 512

Note: For READ_LCONTROLS and DEQ_EVENTQ requests, requests, only one buffer can be specified.

BUFALET

The BUFALET parameter specifies the ALET of each buffer in the buffer list. All the buffers must be in the same address or data space.

BUFNUM

The BUFNUM parameter indicates the number of buffers defined in the BUFLIST list. For READ_LCONTROLS and DEQ_EVENTQ requests, because the system allows only one buffer to be passed, you cannot specify the BUFNUM parameter. For all other requests, when BUFLIST is specified, BUFNUM is required.

BUFINCRNUM

The BUFINCRNUM parameter specifies the size of each BUFLIST buffer in 256-byte increments. Valid values are 1, 2, 4, 8, and 16. For example, a BUFINCRNUM value of 4 indicates that each buffer in the buffer list is 1024 bytes (4 * 256).

For DELETE_ENTRYLIST, READ_LIST, READ_MULT, READ_LCONTROLS, and DEQ_EVENTQ requests, the system requires your buffers to consist of sixteen 256-byte increments and you cannot specify the BUFINCRNUM parameter.

BUFADDRTYPE

The BUFADDRTYPE parameter specifies whether the buffer addresses are real addresses (BUFADDRTYPE=REAL) or virtual addresses (BUFADDRTYPE=VIRTUAL).

BUFADDRSIZE

The BUFADDRSIZE parameter specifies whether the BUFLIST entry address is a 31-bit (BUFADDRSIZE=31) or a 64-bit (BUFADDRSIZE=64) address.