Table 1 shows the format of the VSE header record when IJSYSRC is on a fixed-block-architecture device.
| Offset Dec(Hex) | Size(bytes) Alignment(bits) | Field Name | Description |
|---|---|---|---|
| 0(0) | 2 | CLASRC | Header record identifier. This field is set to X‘FF00’ unless critical data has been destroyed. |
| 2(2) | 4 | LOWLIMIT | Address of low extent. Block number of the first extent of SYSREC. |
| 6(6) | 4 | UPLIMIT | Address of high extent. Block number of the last extent of SYSREC. |
| 10(A) | 1 | Reserved. | |
| 11(B) | 4 | RESTART | Address of record entry area. Block number of the start of the recording area of SYSREC. |
| 15(F) | 7 | Reserved. | |
| 22(16) | 4 | LSTREC | Address of last record. Block number of the last record written on the recording area. |
| 26(1A) | 7 | Reserved. | |
| 33(21) | 1 | DEVCODE | X'0F' Device code for FBA device. |
| 34(22) | 4 | EWMTRK | Early-warning-message block. Block number on which the 90%-full point will be found. |
| 38(26) | 1 | EWMSW | Switch byte: |
| 1... .... | 90%-full-point message has been issued. This switch is turned on by recording routine detecting 90% full point and is turned off by IFCEREP1 when clearing SYSREC. | ||
| .1.. .... | An emergency recording has occurred. This switch is turned on when the system terminates because SYSREC is full. | ||
| ..1. .... | FRAMES | Machine-check and channel-check frames exist on SYSREC. | |
| ...x xxxx | Reserved. | ||
| 39(27) | 1 | SFTYBYT | Check byte. Each bit in this field is set to 1 (X'FF'); used to check the validity of the header-record identifier. |