diff --git a/docs/env.md b/docs/env.md
index 834719a1333..0fe0e1c7363 100644
--- a/docs/env.md
+++ b/docs/env.md
@@ -97,6 +97,20 @@ Description: When nonempty, create pretend prepopulated tokens like "moola" and
 
 Lifetime: until chain is mature enough not to need any pretend tokens
 
+## LMDB_MAP_SIZE
+
+Affects: cosmic-swingset
+
+Purpose: set the minimum size limit for swing-store's LMDB key-value store
+
+Description: default is `2147483648` (2GB), and you need to set higher if you
+receive `Error: MDB_MAP_FULL: Environment mapsize limit reached`
+
+Can always be increased, and does not decrease once a transaction has been
+written with the new mapSize.
+
+Lifetime: until we no longer use LMDB in swing-store
+
 ## OTEL_EXPORTER_PROMETHEUS_HOST
 ## OTEL_EXPORTER_PROMETHEUS_PORT
 
@@ -109,15 +123,21 @@ for the Prometheus scrape endpoint to export telemetry.
 
 Lifetime: until we decide not to support Prometheus for metrics export
 
+## SOLO_LMDB_MAP_SIZE
+
+Affects: solo
+
+Same as `LMDB_MAP_SIZE`, but for solo instead of chain.
+
 ## SOLO_SLOGFILE
 
-Same as SLOGFILE, but for solo instead of chain.
+Same as `SLOGFILE`, but for solo instead of chain.
 
 Lifetime: ?
 
 ## SOLO_SLOGSENDER
 
-Same as SLOGSENDER, but for solo instead of chain.
+Same as `SLOGSENDER`, but for solo instead of chain.
 
 Lifetime: ?
 
diff --git a/packages/cosmic-swingset/src/chain-main.js b/packages/cosmic-swingset/src/chain-main.js
index e0b41526d81..a8e6a522edd 100644
--- a/packages/cosmic-swingset/src/chain-main.js
+++ b/packages/cosmic-swingset/src/chain-main.js
@@ -251,27 +251,29 @@ export default async function main(progname, args, { env, homedir, agcc }) {
     ).pathname;
     const { metricsProvider } = getTelemetryProviders({ console, env });
 
-    const { SLOGFILE, SLOGSENDER } = env;
+    const { SLOGFILE, SLOGSENDER, LMDB_MAP_SIZE } = env;
     const slogSender = await makeSlogSenderFromModule(SLOGSENDER, {
       stateDir: stateDBDir,
     });
 
+    const mapSize = (LMDB_MAP_SIZE && parseInt(LMDB_MAP_SIZE, 10)) || undefined;
+
     // We want to make it hard for a validator to accidentally disable
     // consensusMode.
     const consensusMode = true;
-    const s = await launch(
-      stateDBDir,
+    const s = await launch({
+      kernelStateDBDir: stateDBDir,
       mailboxStorage,
       setActivityhash,
-      doOutboundBridge,
+      bridgeOutbound: doOutboundBridge,
       vatconfig,
       argv,
-      undefined,
       metricsProvider,
-      SLOGFILE,
+      slogFile: SLOGFILE,
       slogSender,
       consensusMode,
-    );
+      mapSize,
+    });
     return s;
   }
 
diff --git a/packages/cosmic-swingset/src/launch-chain.js b/packages/cosmic-swingset/src/launch-chain.js
index 12499ce15c2..5dc73b4a475 100644
--- a/packages/cosmic-swingset/src/launch-chain.js
+++ b/packages/cosmic-swingset/src/launch-chain.js
@@ -12,7 +12,7 @@ import {
   loadSwingsetConfigFile,
 } from '@agoric/swingset-vat';
 import { assert, details as X } from '@agoric/assert';
-import { openSwingStore } from '@agoric/swing-store';
+import { openSwingStore, DEFAULT_LMDB_MAP_SIZE } from '@agoric/swing-store';
 import {
   DEFAULT_METER_PROVIDER,
   exportKernelStats,
@@ -135,7 +135,7 @@ function neverStop() {
   });
 }
 
-export async function launch(
+export async function launch({
   kernelStateDBDir,
   mailboxStorage,
   setActivityhash,
@@ -143,15 +143,18 @@ export async function launch(
   vatconfig,
   argv,
   debugName = undefined,
-  meterProvider = DEFAULT_METER_PROVIDER,
+  metricsProvider = DEFAULT_METER_PROVIDER,
   slogFile = undefined,
   slogSender,
   consensusMode = true,
-) {
+  mapSize = DEFAULT_LMDB_MAP_SIZE,
+}) {
   console.info('Launching SwingSet kernel');
 
-  const { kvStore, streamStore, snapStore, commit } =
-    openSwingStore(kernelStateDBDir);
+  const { kvStore, streamStore, snapStore, commit } = openSwingStore(
+    kernelStateDBDir,
+    { mapSize },
+  );
   const hostStorage = {
     kvStore,
     streamStore,
@@ -159,7 +162,7 @@ export async function launch(
   };
 
   // Not to be confused with the gas model, this meter is for OpenTelemetry.
-  const metricMeter = meterProvider.getMeter('ag-chain-cosmos');
+  const metricMeter = metricsProvider.getMeter('ag-chain-cosmos');
   const METRIC_LABELS = { app: 'ag-chain-cosmos' };
 
   const slogCallbacks = makeSlogCallbacks({
diff --git a/packages/cosmic-swingset/src/sim-chain.js b/packages/cosmic-swingset/src/sim-chain.js
index 430f57f8f96..fed9ccc00ce 100644
--- a/packages/cosmic-swingset/src/sim-chain.js
+++ b/packages/cosmic-swingset/src/sim-chain.js
@@ -86,26 +86,26 @@ export async function connectToFakeChain(basedir, GCI, delay, inbound) {
     env: process.env,
   });
 
-  const { SLOGFILE, SLOGSENDER } = process.env;
+  const { SLOGFILE, SLOGSENDER, LMDB_MAP_SIZE } = process.env;
+  const mapSize = (LMDB_MAP_SIZE && parseInt(LMDB_MAP_SIZE, 10)) || undefined;
   const slogSender = await makeSlogSenderFromModule(SLOGSENDER, {
     stateDir: stateDBdir,
   });
 
   // We don't want to force a sim chain to use consensus mode.
   const consensusMode = false;
-  const s = await launch(
-    stateDBdir,
+  const s = await launch({
+    kernelStateDBDir: stateDBdir,
     mailboxStorage,
-    undefined,
-    undefined,
     vatconfig,
     argv,
-    GCI, // debugName
+    debugName: GCI,
     metricsProvider,
-    SLOGFILE,
+    slogFile: SLOGFILE,
     slogSender,
     consensusMode,
-  );
+    mapSize,
+  });
 
   const { savedHeight, savedActions, savedChainSends } = s;
   const blockManager = makeBlockManager({ ...s, flushChainSends });
diff --git a/packages/solo/src/start.js b/packages/solo/src/start.js
index 25a559f9d8e..ad806ced7ad 100644
--- a/packages/solo/src/start.js
+++ b/packages/solo/src/start.js
@@ -144,8 +144,17 @@ const buildSwingset = async (
     plugin: { ...plugin.endowments },
   };
 
-  const { kvStore, streamStore, snapStore, commit } =
-    openSwingStore(kernelStateDBDir);
+  const {
+    SOLO_SLOGFILE: slogFile,
+    SOLO_SLOGSENDER,
+    SOLO_LMDB_MAP_SIZE,
+  } = process.env;
+  const mapSize =
+    (SOLO_LMDB_MAP_SIZE && parseInt(SOLO_LMDB_MAP_SIZE, 10)) || undefined;
+  const { kvStore, streamStore, snapStore, commit } = openSwingStore(
+    kernelStateDBDir,
+    { mapSize },
+  );
   const hostStorage = {
     kvStore,
     streamStore,
@@ -158,7 +167,6 @@ const buildSwingset = async (
     }
     await initializeSwingset(config, argv, hostStorage);
   }
-  const { SOLO_SLOGFILE: slogFile, SOLO_SLOGSENDER } = process.env;
   const slogSender = await makeSlogSenderFromModule(SOLO_SLOGSENDER, {
     stateDir: kernelStateDBDir,
   });
diff --git a/packages/swing-store/src/swingStore.js b/packages/swing-store/src/swingStore.js
index 8a2b02d2d37..2fd8469751d 100644
--- a/packages/swing-store/src/swingStore.js
+++ b/packages/swing-store/src/swingStore.js
@@ -13,6 +13,8 @@ import { sqlStreamStore } from './sqlStreamStore.js';
 import { makeSnapStore } from './snapStore.js';
 import { initEphemeralSwingStore } from './ephemeralSwingStore.js';
 
+export const DEFAULT_LMDB_MAP_SIZE = 2 * 1024 * 1024 * 1024;
+
 export { makeSnapStore };
 
 export function makeSnapStoreIO() {
@@ -126,12 +128,18 @@ function makeSwingStore(dirPath, forceReset, options) {
   }
   fs.mkdirSync(dirPath, { recursive: true });
 
-  const { mapSize = 2 * 1024 * 1024 * 1024 } = options;
+  const { mapSize = DEFAULT_LMDB_MAP_SIZE } = options;
   let lmdbEnv = new lmdb.Env();
+
+  // Use the new mapSize, persisting if it's bigger than before and there's a
+  // write txn commit.
+  // http://www.lmdb.tech/doc/group__mdb.html#gaa2506ec8dab3d969b0e609cd82e619e5
+  lmdbEnv.resize(mapSize);
+
   lmdbEnv.open({
     path: dirPath,
     mapSize,
-    // Turn off useWritemap on the Mac.  The userWritemap option is currently
+    // Turn off useWritemap on the Mac.  The useWritemap option is currently
     // required for LMDB to function correctly on Linux running under WSL, but
     // we don't yet have a convenient recipe to probe our environment at
     // runtime to distinguish that species of Linux from the others.  For now